Статті в журналах: "Joints de grains – Oxydation"

1

Yao, Peng, Xiaoyan Li, Fengyang Jin, and Yang Li. "Morphology transformation on Cu3Sn grains during the formation of full Cu3Sn solder joints in electronic packaging." Soldering & Surface Mount Technology 30, no. 1 (February 5, 2018): 14–25. http://dx.doi.org/10.1108/ssmt-10-2017-0038.

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Purpose This paper aims to analyze the morphology transformation on the Cu3Sn grains during the formation of full Cu3Sn solder joints in electronic packaging. Design/methodology/approach Because of the infeasibility of analyzing the morphology transformation intuitively, a novel equivalent method is used. The morphology transformation on the Cu3Sn grains, during the formation of full Cu3Sn solder joints, is regarded as equivalent to the morphology transformation on the Cu3Sn grains derived from the Cu/Sn structures with different Sn thickness. Findings During soldering, the Cu3Sn grains first grew in the fine equiaxial shape in a ripening process until the critical size. Under the critical size, the Cu3Sn grains were changed from the equiaxial shape to the columnar shape. Moreover, the columnar Cu3Sn grains could be divided into different clusters with different growth directions. With the proceeding of soldering, the columnar Cu3Sn grains continued to grow in a feather of the width growing at a greater extent than the length. With the growth of the columnar Cu3Sn grains, adjacent Cu3Sn grains, within each cluster, merged with each other. Next, the merged columnar Cu3Sn grains, within each cluster, continued to merge with each other. Finally, the columnar Cu3Sn grains, within each cluster, merged into one coarse columnar Cu3Sn grain with the formation of full Cu3Sn solder joints. The detailed mechanism, for the very interesting morphology transformation, has been proposed. Originality/value Few researchers focused on the morphology transformation of interfacial phases during the formation of full intermetallic compounds joints. To bridge the research gap, the morphology transformation on the Cu3Sn grains during the formation of full Cu3Sn solder joints has been studied for the first time.

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2

Choi, Won Kyoung, Se-Young Jang, Jong Hoon Kim, Kyung-Wook Paik, and Hyuck Mo Lee. "Grain Morphology of Intermetallic Compounds at Solder Joints." Journal of Materials Research 17, no. 3 (March 2002): 597–99. http://dx.doi.org/10.1557/jmr.2002.0084.

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The grain morphology of the intermetallic compound (IMC) that forms at the interface between liquid solders and solid-metal substrates was observed at solder joints. Cu6Sn5 grains on Cu substrates were rough or rounded, and Ni3Sn4 grains on Ni substrates were faceted. Through the energy-based calculations, the relationship between the IMC grain morphology and Jackson's parameter α was explained. The Jackson's parameter of the IMC grain with a rough surface is smaller than 2 while it is larger than 2 for faceted grains.

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3

Lartigue, S., and L. Priester. "Étude des joints de grains dans l'alumine polycristalline." Matériaux & Techniques 73, no. 4-5 (1985): 163–69. http://dx.doi.org/10.1051/mattech/198573040163.

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4

Ding, Cheng Gang, Ya Qi Ni, Chuan Jun Guo, and Gao Feng Quan. "Study on Microstructure and Performance of Bonding-FSSW Hybrid Joints of AZ31 Magnesium Alloy." Advanced Materials Research 295-297 (July 2011): 1915–18. http://dx.doi.org/10.4028/www.scientific.net/amr.295-297.1915.

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In this paper a bonding-FSSW hybrid method is proposed and the performance and microstructure of bonding-FSSW joints of AZ31 aluminum alloy is examined . The results show that the bonding agent has little influence on the forming and mechanical property of FSSW nugget, the shear-resisting property of joints resulted from bonding with sealing glue and FSSW is equivalent to FSSW joints, in bonding-FSSW with high-strength bonding agent, the shear-resisting property of joints are apparently superior to that of pure FSSW or bonding joints. Tiny and uniform equiaxial grains are formed in the WN(Welding nugget zone) and coarse grains are formed in TMAZ (Thermomechanically affected zone) and HAZ (Heat affected zone), but with unequal size.

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5

Ding, Cheng Gang, Ya Qi Ni, Chuan Jun Guo, Gao Feng Quan, and Ji Ping Ge. "Study on Procedure of Bonding-FSSW Hybrid Joints of AZ31 Magnesium Alloy." Advanced Materials Research 314-316 (August 2011): 953–56. http://dx.doi.org/10.4028/www.scientific.net/amr.314-316.953.

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In this paper a bonding-FSSW hybrid method is proposed and the joining procedure as well as the microstructure and performance of bonding-FSSW hybrid joints of AZ31 aluminum alloy is examined . The results show that the bonding agent has little influence on the forming and mechanical property of FSSW nugget, the shear-resisting property of the hybrid joints with sealing glue is equivalent to FSSW joints, in bonding-FSSW hybrid joint with high-strength bonding agent, the shear-resisting property of joints are apparently superior to that of pure FSSW or bonding joints. Tiny and uniform equiaxial grains are formed in the WN(Welding nugget zone) and coarse grains are formed in TMAZ (Thermomechanically affected zone) and HAZ (Heat affected zone), but with unequal size. The good properties of the hybrid joints are obtained by choosing the optimal joining parameter.

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6

Zhang, Yongqiang, Xiangyi Xue, Jingli Zhang, Huiming Li, Ping Guo, Hao Pan, Hongmiao Hou, and Guoyu Jia. "Microstructure Control of Welded Joints of Dissimilar Titanium Alloys by Isothermal Forging." Materials 13, no. 15 (July 28, 2020): 3347. http://dx.doi.org/10.3390/ma13153347.

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In this study, the welded joints of dissimilar titanium alloys Ti600/Ti-22Al-25Nb were strengthened by isothermal forging. Different deformation parameters, including temperature, deformation speed, and reduction, were chosen. By isothermal forging, the original coarse dendritic grains of the welded joints were broken up effectively to form a large number of equiaxed grains. Meanwhile, many second phases were precipitated in the grain. Additionally, the dynamic globularization kinetics of second phases within the welded joints were quantitatively characterized and investigated. The results showed that the dynamic globularization kinetics and globularization rate were sensitive to the deformation conditions, and were promoted by a reduced strain rate and an elevated deformation temperature.

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7

Le Cloirec, P., P. Horny, and A. Ladousse. "Anaerobic Biological Removal of Dimethyldisulfide in a Chemical Process Wastewater." Water Science and Technology 26, no. 9-11 (November 1, 1992): 2069–72. http://dx.doi.org/10.2166/wst.1992.0663.

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The capability and performances of anaerobic biological removal of dimethyldisulfide were studied with a biofilter packed with a mixture of activated carbon and calcium carbonate grains. The oxygen sources of the bio-oxydation came from nitrates used like nutrients. The operating conditions (pH, volumetric load…) were determined. The quantification of the nutrients (DMDS, Nitrates) and by-products (Sulfates) in the influent and the effluent enabled us to approach the mechanisms of degradation of dimethyldisulfide.

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8

Seo, Sun-Kyoung, Moon Gi Cho та Hyuck Mo Lee. "Crystal orientation of β-Sn grain in Ni(P)/Sn–0.5Cu/Cu and Ni(P)/Sn–1.8Ag/Cu joints". Journal of Materials Research 25, № 10 (жовтень 2010): 1950–57. http://dx.doi.org/10.1557/jmr.2010.0253.

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Electron backscatter diffraction analysis was used to compare the crystal orientation of β-Sn grains in Ni(P)/Sn–0.5Cu/Cu and Ni(P)/Sn–1.8Ag/Cu joints before and after aging. In Ni(P)/solder/Cu joints, the solder composition (Cu versus Ag) significantly affects β-Sn grain orientation. In Ni(P)/Sn–0.5Cu/Cu, there are two types of small columnar grains grown from Ni(P) and Cu under bump metallurgy with a high-angle grain boundary crossing the joint closer to the Ni side; in contrast, Ni(P)/Sn–1.8Ag/Cu has large grains with low-angle boundaries. During thermal aging at 150 °C for 250 h, the Ni(P)/Sn–0.5Cu/Cu joints undergo a more significant microstructural change than the Ni(P)/Sn–1.8Ag/Cu joint. Additionally, obvious ledges developed along the high-angle grain boundary between the upper and lower areas in the Sn–0.5Cu joint.

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9

Yu, Si Rong, and Xian Jun Chen. "Microstructures and Properties of FSW Joints of AZ31B Mg Alloy." Advanced Materials Research 291-294 (July 2011): 855–59. http://dx.doi.org/10.4028/www.scientific.net/amr.291-294.855.

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The extruded AZ31B Mg alloy sheet was welded with friction stir welding. The microstructures and mechanical properties of the welded joint were investigated. The results show that the grains in the weld nugget zone were small, uniform and equiaxed. The grains in thermo-mechanical affected zone were stretched and relatively small, but were not as small and uniform as those in the weld nugget zone. The grains in the heat-affected zone were relatively coarse. The fracture of the welded joint occurred mainly in the heat affected zone. The tensile strength of the welded joints was up to 257.4 MPa and was 87.9% of the base material strength. The microhardness in the weld nugget zone was higher. The microhardness in the thermo-mechanical affected zone and heat affected zone were lower than that in the weld nugget zone. The microhardness in the weld nugget zone increased from the upper surface to the bottom.

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10

Guiraldenq, G. "Historique et évolution des recherches sur les joints de grains." Matériaux & Techniques 80, no. 6-7-8 (1992): 23–28. http://dx.doi.org/10.1051/mattech/199280060023.

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11

Gourlay, C. M., Zhao Long Ma, Jing Wei Xian, Sergey A. Belyakov, Mohd Arif Anuar Mohd Salleh, Guang Zeng, Hideyuki Yasuda, and Kazuhiro Nogita. "Solidification of Sn-3Ag-0.5Cu and Sn-0.7Cu-0.05Ni Solders." Materials Science Forum 857 (May 2016): 44–48. http://dx.doi.org/10.4028/www.scientific.net/msf.857.44.

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The solidification of Sn-3Ag-0.5Cu and Sn-0.7Cu-0.05Ni are overviewed and compared. In joints on Cu substrates, both solders begin solidification with primary Cu6Sn5 growing in the bulk liquid prior to tin nucleation. In freestanding balls and joints, SAC305 generally solidifies with a single tin nucleation event and exhibits a mutually-twinned tin grain structure. In contrast, SN100C BGA balls and joints exhibit multiple independent tin grains that grow as a columnar array in joints.

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12

Qianzhong, Jia, Li Man, Qu Fuzheng, and Zhang Hongtao. "Influence of Holding Time on Properties of Cemented Carbide-polycrystalline Diamond Compact Joints." Open Materials Science Journal 9, no. 1 (June 26, 2015): 33–38. http://dx.doi.org/10.2174/1874088x01509010033.

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The influence of brazing holding time on properties of cemented carbide-polycrystalline diamond (PCD) compact joints were investigated in this study. The microstructure and phase composition of joints were investigated by scanning electron microscopy, electron probe microanalyzer, and X-ray diffraction. Microstructural investigations revealed the presence of Ag-based solid solution, Cu-based solid solution, Cu0.64Zn0.36, and a small amount of MnNi phase at the joint interface. The max shear strength of brazed joints 350.6 MPa was determined in the samples joined at 15 s, which was partially due to the dispersion strengthening effect of gray-black grains containing Cu-based solid solution, Cu0.64Zn0.36 and MnNi phase in the joints. Equal-area-circle grain diameter of the gray-black grains grew with longer holding time, whereas the shear strength decreased because of the formation of continuous intermetallic compounds layer along the joint boundary. Thermal damage of the PCD layer also deteriorated with increased holding time, and hence shorter holding time was preferable in the production.

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13

Lemiti, M., S. Audisio, C. Mai, and B. Balland. "Evolution de la taille des grains du silicium polycristallin pendant des traitements thermiques ou oxydation." Revue de Physique Appliquée 24, no. 2 (1989): 133–41. http://dx.doi.org/10.1051/rphysap:01989002402013300.

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14

Sun, Zhuanping, Xinqi Yang, and Shuxin Li. "Characteristics of Friction Plug Joints for AA2219-T87 FSW Welds." Materials 15, no. 4 (February 18, 2022): 1525. http://dx.doi.org/10.3390/ma15041525.

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In this study, Friction plug welding (FPW) for 8 mm thickness AA2219-T87 sheets were carried out, and defect-free joints were obtained. The geometric size of plug and plate hole, rotational speed and welding force exhibit significant effects on the weld formation. Meanwhile, it is concluded that significant inhomogeneity of microstructure and mechanical properties exists in FPW joints. The recrystallization zone has the highest mechanical properties owing to the fine equiaxed grains and uniformly distributed θ precipitates. The entire plug, thermo-mechanically affected zone and nugget thermo-mechanically affected zone closed to the bonding interface are significantly softened due to the deformation of the grains and θ’ precipitate dissolution. The ultimate tensile strength (UTS) and elongation of the FPW joints can reach 359 MPa and 7.3% at 77 K and 305 MPa and 5% at 298 K, respectively.

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15

Zhang, Zhi Jun, Bo Lin He, Zong Min Lv, and Kang Wei. "Review the Effect of Welding Processes on the Comprehensive Mechanical Properties of Magnesium Alloy Joints." Applied Mechanics and Materials 716-717 (December 2014): 184–87. http://dx.doi.org/10.4028/www.scientific.net/amm.716-717.184.

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In this paper, the effect of welding processes such as friction stir welding (FSW), laser beam welding (LBW) and pulsed current gas tungsten arc welding (PCGTAW) on comprehensive mechanical properties of AZ31B magnesium alloy was reviewed. Among the three different welding processes, the LBW joints showed superior comprehensive properties to FSW and PCGTAW joints. The formation of very fine grains in weld region, higher fusion zone hardness, uniformly distributed finer precipitates were the main reasons for superior comprehensive mechanical performance of LBW joints compared to PCGTAW and FSW joints.

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16

Fushimi, Takahito, Yo Tanaka, Shinnosuke Soda, Tomoki Matsuda, Tomokazu Sano, and Akio Hirose. "Thermal Fatigue Properties of Ultrasonically Bonded Copper Joints." Applied Sciences 9, no. 8 (April 15, 2019): 1556. http://dx.doi.org/10.3390/app9081556.

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Thermal fatigue generally occurs in ultrasonically bonded copper joints in electronic devices as the bonding substrate is composed of plural materials, leading to differences in the coefficient of thermal expansion. In this study, we found that the thermal fatigue resistance of the ultrasonically bonded copper joints was influenced by the grain size and hardness of the bonding substrate through the evaluation of the thermal fatigue properties. Copper alloys C1020 and C1940 were used as substrate materials to investigate the influence of the initial properties of the bonding material on the thermal fatigue resistance. We evaluated the crack propagation due to thermal fatigue via thermal cycle tests. Microstructural observations of the region fractured because of thermal fatigue revealed that cracks resulting from thermal fatigue did not progress in the fine grain region formed at the bonded interface. It was inferred that grain boundaries were an obstacle to crack propagation. C1940 has higher hardness and finer grains than C1020, and showed a lower decreasing rate of the peel strength and bonding area after the thermal cycling test than C1020 joints. Thus, a hard copper material with fine grains is effective in suppressing thermal fatigue fracture of ultrasonically bonded copper joints.

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17

Cadel, E., D. Lemarchand, S. Chambreland, and D. Blavette. "Structure et chimie locale des joints de grains dans les superalliages." Le Journal de Physique IV 09, PR4 (April 1999): Pr4–147—Pr4–152. http://dx.doi.org/10.1051/jp4:1999419.

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18

Wang, Shan Lin, Heng Yv Zhang, and Xing Li. "Characteristics of Microstructure and Microhardness of Friction Stir Welded Joints for AZ31 Magnesium Alloy." Applied Mechanics and Materials 472 (January 2014): 612–16. http://dx.doi.org/10.4028/www.scientific.net/amm.472.612.

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The joints of magnesium alloy plate with 4 mm thickness was successfully welded by friction stir welding, and the characteristics in microstructure and microhardness of joints after heat treatment were investigated. The results indicate that the tensile strength of as welded joint exceeds 220 MPa, nearly 83% strength of basic metals. During heat treatment, the grains in nugget zone grow gradually, while the grain recrystallization was occurred in heat affected zone and basic metal zone when the temperature is 150°C. As the temperature increases continuously, the grains will grow obviously. The average microhardness of joint will increase and reaches a maximum of 73 Hv at 250°C, and then will decrease sharply with increase of heat treatment temperature.

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19

Iwamoto, Chihiro, Shinobu Satonaka, and Yoshihito Kawamura. "Microstructure and Mechanical Properties of Mg₉₆Zn₂Y₂ Joints Welded by Resistance Spot Welding." Materials Science Forum 706-709 (January 2012): 1187–92. http://dx.doi.org/10.4028/www.scientific.net/msf.706-709.1187.

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Mg96Zn2Y2 is widely studied due to its high tensile yield strength and elongation. These excellent properties were considered to relate to the nanostructure of the alloy such as fine-grained α-Mg matrix and bent long period stacking ordered (LPSO) structure. In order to extend the application of this Mg alloy, development of the welding technique is indispensable. In the light of the reliability and productivity, resistance spot welding is an attractive method to join this Mg alloy. In this study, we joined the Mg alloys by the resistance spot welding with cover plates. Mechanical properties and structures of the nugget of the joints were investigated. In the case of the joints welded with cover plates, the welded region of the Mg alloy sheets were covered with steel plates to supply adequate heat for welding. Joints of extruded Mg96Zn2Y2 were obtained at relatively low welding current. The tensile strength of Mg96Zn2Y2 alloy was higher than that of the commercial Mg alloy AZ31B joints. Mg96Zn2Y2 base alloy had extended LPSO phase along extruded direction in α-Mg grains. At the nugget, net-like secondary phase was produced in the Mg grains. The relationship between the microstructure in the joints and mechanical properties were discussed.

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20

Xie, Miao-Xia, Yan-Xin Li, Xiang-Tao Shang, Xue-Wu Wang, and Jun-Yu Pei. "Microstructure and Mechanical Properties of a Fiber Welded Socket-Joint Made of Powder Metallurgy Molybdenum Alloy." Metals 9, no. 6 (June 2, 2019): 640. http://dx.doi.org/10.3390/met9060640.

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Fiber welding of socket-joints made of nanostructured high-performance molybdenum alloy (NS Mo) was carried out to get a better understanding of the role of welding heat input. It was found that low heat input (i.e., high welding speed) resulted in significantly refined grains in the fusion zone (FZ) of fiber laser welded NS Mo joints. When welding heat input decreased from 3600 J/cm (i.e., 1.2 kW, 20 cm/min) to 250 J/cm (i.e., 2.5 kW, 600 cm/min), the tensile strength of welded joints increased from about 250 MPa to about 570 MPa. It was confirmed by energy spectrum analysis that the higher the welding heat input, the higher the oxygen contents at the grain boundary (GB) within the FZ. In addition, the most important reason for poor strength of welded joints of Mo alloys was reported as being that MoO2 was segregated on the grain boundary. Therefore, it was concluded that welding under low heat input (i.e., high welding speed) was able to reduce the segregation degree of MoO2 at the grain boundary by refining grains and increasing the total area of GBs, thus improving the strength of welded joints and reducing the proportion of the intergranular fracture zone in tensile fractures.

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21

Ju, Guokui, Fei Lin, Wenzhen Bi, Yongjiu Han, Wang Junjie, and Xicheng Wei. "Study of IMC at interfaces of Sn3.0Ag0.5Cu3.0Bi0.05Cr/Cu joints during thermal ageing." Soldering & Surface Mount Technology 26, no. 4 (August 26, 2014): 173–79. http://dx.doi.org/10.1108/ssmt-08-2013-0022.

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Purpose – The purpose of this study was to comparatively investigate interfacial intermetallic compounds (IMCs) in the Sn3.0Ag0.5Cu3.0Bi0.05Cr/Cu (SACBC/Cu) and Sn3.0Ag0.5Cu/Cu (SAC/Cu) solder joints, and to determine any differences. Design/methodology/approach – The samples were annealed after isothermal ageing at 150°C for 0, 168 and 500 hours, and their cross-sections were observed by scanning electron microscopy and energy dispersive spectroscopy. Findings – The interfacial IMC morphology in two joints had significant differences. For the Cu/SAC/Cu joints, the granular and short rod-like Ag3Sn particles attached on the surface and boundary of interfacial Cu6Sn5 grains were detected, and they coarsened observably with ageing time at 150°C, and lastly embedded at the grain boundaries. However, for the Cu/SACBC/Cu joints, there were tiny filamentous Ag3Sn growing on the surface of interfacial Cu6Sn5 grains, and the Ag3Sn had a tendency to break into nanoparticles, which would be distributed evenly and cover the IMC layer, profiting from the Bi and Cr precipitates from solder matrix during ageing. Originality/value – The paper implies that the addition of Bi and Cr could affect the IMCs of joints, thereby delaying interfacial reactions between Sn and Cu atoms and improving the service reliability. The SACBC solder is a potential alloy for electronic packaging production.

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22

TEJONADHA BABU, K., S. MUTHUKUMARAN, C. SATHIYA NARAYANAN, and C. H. BHARAT KUMAR. "ANALYSIS AND CHARACTERIZATION OF FORMING BEHAVIOR ON DISSIMILAR JOINTS OF AA5052-O TO AA6061-T6 USING UNDERWATER FRICTION STIR WELDING." Surface Review and Letters 27, no. 03 (July 18, 2019): 1950121. http://dx.doi.org/10.1142/s0218625x1950121x.

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The effects of underwater friction stir welding (UFSW) on mechanical properties, strain hardening behavior, and formability of dissimilar materials of AA5052-O and AA6061-T6 welded joints were investigated. The mechanical properties of the UFSW joints exhibited higher strength and higher joint efficiency than the conventional friction stir welded joints (CFSW). The maximum joint efficiency of 73% has been attained for UFSW joints, which is due to the effect of welding atmosphere. The hardness of the stir zone (SZ) and heat affected zone (HAZ) are also obtained higher for the UFSW joints. Moreover, the hardening capacity, strain hardening exponent and formability of the UFSW joints were greatly improved over the CFSW joints. The improvement in mechanical properties of the UFSW joints is mainly due to faster cooling rate during welding. The microstructural characteristics revealed the formation of fine grains in the UFSW joints compared to the CFSW joints.

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23

Wang, Hua, Yun Peng Zhang, and Xiao Yu Zhang. "TZM Alloy TIG Welding Process and Microstructure of Welded Joints." Advanced Materials Research 291-294 (July 2011): 867–71. http://dx.doi.org/10.4028/www.scientific.net/amr.291-294.867.

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In this paper, the effect of welding current of the tungsten inert gas arc (TIG) welding process on weld quality of TZM alloy was investigated and the fracture microstructure and mechanical properties of the welding joints of TZM alloy was analyzed by x-ray flaw detection, metallographic microscopic analysis, scanning electron microscopy and mechanical properties test. The results indicate that the weld bead with excellent mechanical properties can be obtained using the welding process parameter with the welding current of 210A, welding speed of 4 mm/s and the argon gas flow rate of 8~12 L/min. The microstructure of weld presents the large columnar grains in the center of the weld bead and the equiaxed grains in heat-affected zone instead of the lamellar fiber texture of the TZM alloy matrix, which resulted in the weakened strength of the matrix and the improved plasticity of it.

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24

Chiu, Ying-Ta, Kwang-Lung Lin, and Yi-Shao Lai. "Orientation transformation of Pb grains in 5Sn–95Pb/ 63Sn–37Pb composite flip-chip solder joints during electromigration test." Journal of Materials Research 23, no. 7 (July 2008): 1877–81. http://dx.doi.org/10.1557/jmr.2008.0227.

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Microstructural evolution occurred in 5Sn–95Pb/63Sn–37Pb composite flip-chip solder bump during electromigration. Scanning electron microscopy (SEM) and electron backscatter diffraction (EBSD) observations for 5Sn–95Pb/63Sn–37Pb composite flip-chip solder joints subjected to 5 kA/cm2 current stressing at 150 °C revealed a gradual orientation transformation of Pb grains from random textures toward (101) grains. We proposed that the combination of reducing the surface energy of Pb grain boundaries and resistance of the entire polycrystalline system are the driving force for the orientation transformation of Pb grains during an electromigration test.

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25

Xu, Xiangjun, Junpin Lin, Jian Guo, and Yongfeng Liang. "Friction Weldability of a High Nb Containing TiAl Alloy." Materials 12, no. 21 (October 30, 2019): 3556. http://dx.doi.org/10.3390/ma12213556.

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The friction weldability of Ti-45Al-8.5Nb-0.2W-0.2B-0.02Y alloy has been investigated by optimizing process parameters and analyzing the microstructures and tensile properties of the joints. The as-cast alloy with a nearly lamellar (NL) microstructure and the as-forged alloys with a duplex (DP) microstructure have been successfully welded. All the joints have a severe deformation zone (SDZ) and a transition zone (TZ) between the parent metal (PM) and SDZ. SDZ, showing a biconcave lens geometry, has a maximum thickness of hundreds of micrometers at the periphery. TZ is hundreds of micrometers thick. All SDZs have a fine-grained DP microstructure with a grain size of a few micrometers. For the joint of the as-cast alloy, the TZ consists of deformed lamellar colonies as the major constituent and partially recrystallized grains as the minor constituent. For the joint of the as-forged alloy, the TZ is similar to both the PM and SDZ, showing a DP microstructure. The grain size, volume fraction of γ grains, and the remnant lamellar colonies all increase with the distance from the SDZ. All joints presented perfect metallurgical bonding. The strengths of the joints are higher than those of the corresponding PMs. This indicates that the studied alloy has good friction weldability.

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26

Mudiantoro, Sunoto, Winarto Winarto, and Herry Oktadinata. "Microstructure Evolution and Distribution of Mechanical Properties in Shielded Metal Arc Welded Dissimilar DSS 2205 and HY80 Joints." MATEC Web of Conferences 269 (2019): 06004. http://dx.doi.org/10.1051/matecconf/201926906004.

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Анотація:

Dissimilar welding is a unique and complex process because in each zone in the different welding area have unique structures and characteristics. The modified structure may have a significant effect on weld metal properties. In this research, the primary objective is to investigate the microstructure evolution and hardness distribution mode of a different joint HY80 steel plate and Duplex type 2205 welded by using thick weld or shielded metal arc weld (SMAW). The microstructure of weld metal zones was observed. The test plates were welded in both butt joint and fillet joint by using E309L filler metal. It was found that the 309L electrode provides the equilibrium between austenite and ferrite phase in the different weld metal zones of DSS 2205 and HY80 steel joint. The results show that hardness distribution of different joint of both butt weld and fillet weld presents sinusoidal trend, where hardness in HAZ is highest. The peak value of hardness appeared in HY 80 base metal near the fusion line. The microstructure of base metal DSS 2205 shows fine grains of ferrite and austenite grains with dark and light shades respectively. The microstructure of weld metal shows coarse grains of austenite along with some slag inclusions as dark spots. The Heat Affected Zone of HY80 steel plate shows coarse grains of austenite and ferrite, while the heat affected zone of DSS 2205 shows thin fusion line with coarse grains of ferrite as dark zones and coarse grains of austenite as light zones. There is, a degree of variation in weld metal ferrite content was observed. Keywords: Duplex Stainless Steel, HY80, SMAW, Dissimilar Joint, Hardness, and Impact Toughness.

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27

Pélissonnier-Grosjean, C., D. Fournier, and A. Thorel. "Résistance thermique d'interface aux joints de grains dans le nitrure d'aluminium polycristallin." Le Journal de Physique IV 09, PR4 (April 1999): Pr4–201—Pr4–206. http://dx.doi.org/10.1051/jp4:1999426.

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28

Poulat, S., B. Décamps, L. Priester, and J. Thibault. "Ségrégation intergranulaire et accommodation des dislocations extrinsèques dans les joints de grains." Le Journal de Physique IV 09, PR4 (April 1999): Pr4–249—Pr4–254. http://dx.doi.org/10.1051/jp4:1999433.

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29

Simões, Sónia, Filomena Viana, Ana Ramos, M. Vieira, and Manuel Vieira. "Microstructural Characterization of Dissimilar Titanium Alloys Joints Using Ni/Al Nanolayers." Metals 8, no. 9 (September 12, 2018): 715. http://dx.doi.org/10.3390/met8090715.

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This study demonstrates the potential of the use of Ni/Al nanolayers for joining dissimilar titanium alloys. For this purpose, a detailed microstructural characterization of the diffusion bonding interfaces of TiAl to Ti6Al4V, TiAl to TiNi and TiNi to Ti6Al4V was carried out. The nanolayers (alternated aluminum and nickel (Ni-7V wt.%) layers) were deposited onto the base material surfaces. Diffusion bonding was performed at 700 and 800 °C under pressures ranging from 5 to 40 MPa and at dwell times between 60 and 180 min. Microstructural characterization was performed using high resolution transmission and scanning electron microscopies. The results revealed that dissimilar titanium joints (TiAl to Ti6Al4V, TiAl to TiNi and TiNi to Ti6Al4V) assisted by Ni/Al nanolayers can be obtained successfully at 800 °C for 60 min using a pressure of 20 MPa. The bond interfaces are thin (less than 10 µm) and mainly composed of NiAl grains with a few nanometric grains of Al8V5. Thin layers of Al-Ni-Ti intermetallic compounds were formed adjacent to the base materials due to their reaction with the nanolayers.

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30

Bijanrostami, Khosro, and Reza Vatankhah Barenji. "Underwater dissimilar friction stir welding of aluminum alloys: Elucidating the grain size and hardness of the joints." Proceedings of the Institution of Mechanical Engineers, Part L: Journal of Materials: Design and Applications 233, no. 4 (January 16, 2017): 763–75. http://dx.doi.org/10.1177/1464420716686625.

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Underwater dissimilar friction stir welding of the AA6061 and AA7075 aluminum alloys was performed in this study. The effect of friction stir welding parameters on the grain size and hardness of the joints was studied using empirical models. The microstructure of the joints was characterized by means of light and transmission electron microscopes. The Vickers hardness test was conducted to measure the hardness of the joints. In addition, the process parameters including traverse and rotational speeds, grain size and hardness of the joints were correlated. The results revealed that the developed models predicted the hardness and grain size of the joints, precisely. Higher traverse speed and lower rotational speeds resulted in finer grain size and larger hardness. The grain boundaries and dislocations were identified as responsible for the higher hardness of the joints welded at lower heat input conditions. Moreover, the Hall–Petch relationship showed a deviation from its linear classical equation, which was due to the formation of substructures such as dislocations inside the grains.

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31

Liu, Yan, Zheng Ren Huang, and Xiu Jian Liu. "Reaction Layer Microstructure of SiC/SiC Joints Brazed by Ag-Cu-Ti Filler Metal." Key Engineering Materials 434-435 (March 2010): 202–4. http://dx.doi.org/10.4028/www.scientific.net/kem.434-435.202.

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Abstract. The reaction layer microstructure of SiC/SiC joints brazed by Ag-Cu-Ti filler metal, including composition, morphology, grain size were investigated by X-ray diffraction, electronic probe microanalysis, transmission electron microscope. An obvious reaction layer composed of TiC and Ti5Si3 was observed at the interface of SiC substrate and filler metal. There is a representative structure of SiC substrate/continuous fine TiC layer /discontinuous coarse Ti5Si3 layer/filler metal in the reaction layer. The continuous TiC layer, composed of about 10 nm roundish grains, is 350 ~ 400 nm thick. Ti5Si3 layer is composed of only one row of Ti5Si3 grains, which disperse with diverse size from 100 ~ 500 nm. Different growth behavior of TiC and Ti5Si3 is the main reason to form this microstructure.

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32

Sevvel, P., and V. Jaiganesh. "Investigation on Evolution of Microstructures and Characterization During FSW of Az80a Mg Alloy." Archives of Metallurgy and Materials 62, no. 3 (September 26, 2017): 1779–85. http://dx.doi.org/10.1515/amm-2017-0270.

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Abstract Experimental investigation was conducted to find out microstructural characteristic changes arising in the weldments AZ80A Mg alloys obtained using the friction stir welding. Tools with three different pin profile geometries were employed during this investigation at constant tool rotational speed and feed rate. Tensile tests are performed and the tensile fracture surfaces are examined using the Scanning Electron Microscope (SEM) and the obtained SEM images are used for microstructural investigations. From the experimental results, it was observed that the geometry of the tool pin plays a significant role in producing essential stirring action there by regulating the flow of the plasticized material and leading to the formation of small sized grains having equally distributed fine strengthening precipitates. These structured grains have a direct reflecting impact in increasing the hardness and mechanical properties of the fabricated joints at the nugget zone of the friction stir welded AZ80A Mg alloy joints.

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33

Liu, Pengtao, Runze Yu, Xinhuan Gao, and Guanzhen Zhang. "Influence of Surface Ultrasonic Rolling on Microstructure and Corrosion Property of T4003 Ferritic Stainless Steel Welded Joint." Metals 10, no. 8 (August 11, 2020): 1081. http://dx.doi.org/10.3390/met10081081.

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In this paper, the effect of surface ultrasonic rolling treatment (SURT) on surface properties of T4003 cold metal transfer (CMT) welded joints was studied. Surface topography and microstructure changes of the welded joint surface before and after SURT were observed by optical microscope and scanning electron microscope. The hardness and residual stress distribution of welded joint were measured by a microhardness tester and X-ray diffractometer. The change of corrosion resistance of welded joints was studied by electrochemical polarization curve measurement. The results show that surface roughness (Ra) of the weld zone, heat affect zone (HAZ), and base metal after SURT was reduced to 0.320 μm, 0.156 μm, and 0.227 μm, respectively, and surface morphology became smooth. The plastic deformation layer and working hardening layer were formed at the welded joint. The degree of plastic deformation of the weld zone was more serious than that in the base metal, and grains in weld zone was obviously refined. The thickness of plastic deformation layer was about 100 μm. The surface hardness in the weld zone was highest, which is about 420 HV. The refinement of grains and the increase of surface hardness can improve the fatigue life of welded joint. After SURT, the residual stress in the welded joint changes from residual tensile stress to residual compressive stress, which can also improve fatigue life of the welded joint. Surface corrosion resistance of welded joints after SURT was improved due to smooth surface and the formation of fine grains layer.

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34

Paul, H., J. Morgiel, T. Baudin, F. Brisset, M. Prażmowski, and M. Miszczyk. "Characterization of Explosive Weld Joints by TEM and SEM/EBSD." Archives of Metallurgy and Materials 59, no. 3 (October 28, 2014): 1129–36. http://dx.doi.org/10.2478/amm-2014-0197.

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Abstract The layers near the interface of explosively welded plates were investigated by means of microscopic observations with the use of transmission electron microscopy (TEM) equipped with energy dispersive spectrometry and scanning electron microscopy equipped with electron backscattered diffraction facility (SEM/EBSD). The metal compositions based on carbon or stainless steels (base plate) and Ti, Zr and Ta (flyer plate) were analyzed. The study was focused on the possible interdiffusion across the interface and the changes in the dislocation structure of bonded plates in the layers near-the-interface.It was found that the extremely rapid temperature increase followed by high cooling rates in the areas near the interface favour the formation of metastable phases. The crystalline or glassy nature of the phases formed inside melted zones strongly depends on the chemical composition of bonded metals. The amorphous phases dominates the melted zone of the (carbon or stainless steel)/Zr whereas the mixture of amorphous phases and nano- grains were identified in (carbon steel)/Ti and (stainless steel)/Ta clads. The elongated shape of the (sub)grains and the randomly distributed dislocations inside them as well as the shear bands and twins observed in the layers near-the-interface of all investigated clads, clearly indicated that during explosive welding, the deformation processes were prevailing over the softening ones.

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35

No, Kookil, Ye Rim Lee, Jong Hoon Yoon, Joon Tae Yoo, and Ho Sung Lee. "Tensile Properties and Microstructure of Friction Stir Welded Joints 2195-T8 Aluminum Alloy." Applied Mechanics and Materials 835 (May 2016): 191–96. http://dx.doi.org/10.4028/www.scientific.net/amm.835.191.

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Friction stir welding is a widely used welding process for aluminum alloys because it avoids many of the problems of conventional fusion welding. This process is beneficial especially for lithium containing aluminum alloys in which the reactive property of element Li causes porosity and hot cracking during melting and solidification. In friction stir welding process, each region undergoes different thermo-mechanical cycles and produces a non-homogeneous microstructure. In the present study, the mechanical properties and microstructure of a 2195-T8 aluminum alloy joined with friction stir welding were investigated. The change in microstructure across the welded joint was found to correspond to microhardness measurement. The microstructure was characterized by the presence of severely deformed grains and fine recrystallized grains depending on the region. Tensile tests shows the optimum condition was obtained at the tool rotating speed of 600rpm and the traveling speed range from 180 to 300mm/min.

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36

Merda, Agata, Grzegorz Golański, Paweł Wieczorek, and Kamil Staszałek. "The Analysis of the Microstructure of Welded Joints in Steel P5 after Service." Biuletyn Instytutu Spawalnictwa, no. 5 (October 2020): 7–12. http://dx.doi.org/10.17729/ebis.2020.5/1.

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The material subjected to the tests discussed in the article was a section of a welded joint made of bainitic steel P5. The joint subjected to analysis was sampled from a pipe section exposed to the effect of elevated temperature for more than 96 000 hours. The metallurgical tests revealed a relatively low degree of the degradation of the test joint. The microstructure contained retained bainite and precipitates of various morphology. The identification of precipitates revealed the presence of M23C6 and M2C precipitates in the joint. The M23C6 carbides were observed along the boundaries of former austenite grains. The above-named identification of precipitates also revealed the presence of M2C and M23C6 C6 carbides within the grains/laths. The insignificant exhaustion of the joint microstructure might be ascribed to the fact that the joint was subjected to relatively low temperature for a relatively short time.

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37

Lopatin, Nikolay, Kirill Senkevich, and Egor A. Kudryavtsev. "Effect of Microstructure State of Titanium Alloy Ti-6Al-4V on Structure and Mechanical Properties of Joints Produced by Diffusion Bonding Process." Materials Science Forum 783-786 (May 2014): 2659–64. http://dx.doi.org/10.4028/www.scientific.net/msf.783-786.2659.

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The studies of diffusion bonded samples of Ti-6Al-4V and Nitinol alloys were carried out considering the titanium alloy in two states: ultra-fine grained and bi-modal microstructures, the last one consisted of small and large α-phase grains. Depending on microstructure and chemical composition of the alloys, the diffusion bonding had been made at temperatures from 600°C to 850°C. The microstructures of joints was studied by scanning electron microscope using detector of backscattering electron diffraction. The shear strengths of joints were measured. It was concluded that the ultra-fine grained Ti-6Al-4V alloy could be applied for joints manufactured at a temperature lower than 750°C. The bi-modal Ti-6Al-4V alloy is an effective material for producing the joints at the temperature larger that 750°C.

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38

Liu, Xu, Ruiling Jia, Huixia Zhang, Wenhua Cheng, and Xiwei Zhai. "EBSD Characterization of the Microstructure of 7A52 Aluminum Alloy Joints Welded by Friction Stir Welding." Materials 14, no. 21 (October 24, 2021): 6362. http://dx.doi.org/10.3390/ma14216362.

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The microstructure and texture of materials significantly influence the mechanical properties and fracture behavior; the effect of microstructure in different zones of friction stir-welded joints of 7A52 aluminum alloy on fracture behavior was investigated in this paper. The microstructural characteristics of sections of the welded joints were tested using the electron backscattered diffraction (EBSD) technique. The results indicate that the fracture is located at the advancing side of the thermomechanically affected zone (AS-TMAZ) and the stir zone (SZ) interface. The AS-TMAZ microstructure is vastly different from the microstructure and texture of other areas. The grain orientation is disordered, and the grain shape is seriously deformed under the action of stirring force. The grain size grows unevenly under the input of friction heat, resulting in a large amount of recrystallization, and there is a significant difference in the Taylor factor between adjacent grains and the AS-TMAZ–SZ interface. On the contrary, there are fine and uniform equiaxed grains in the nugget zone, the microstructure is uniform, and the Taylor factor is small at adjacent grains. Therefore, the uneven transition of microstructure and texture in the AS-TMAZ and the SZ provide conditions for crack initiation, which become the weak point of mechanical properties.

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39

Zawadzki, Paweł. "Proposal for a Novel Abrasive Machining Method for Preparing the Surface of Periarticular Tissue during Orthopedic Surgery on Hip Joints." Journal of Functional Biomaterials 12, no. 3 (September 8, 2021): 50. http://dx.doi.org/10.3390/jfb12030050.

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Drilling, cutting, and milling are the most common methods used in orthopedic surgery. However, popular machining methods do not obtain the complex shape of the periarticular tissue surfaces, increasing operation time and patient recovery. This paper reports an attempt to research a novel design of a machining process for surgical procedures. A device using abrasion machining based on mechanical erosion was proposed. Machining uses an undefined geometry of the cutting grains to cut tissue in any direction during oscillatory tool movement. This new concept is based on a cylindrical abrasive device made of brown fused alumina and silicon carbide grains deposited with an epoxy resin binder on the surface of a polyamide shaft. The best results in terms of machining efficiency were obtained for grains of the BFA80 type. Cutting experiments with different values in terms of cutting speed, granulation of the abrasive grains, pressure forces, and machining scope showed that the proposed concept, by developing the shape of the device, allows for penetration of the tissue structure. The research shows the possibility of using the proposed method during periarticular tissue machining.

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40

Watanabe, Mitsuhiro, and Shinji Kumai. "Welding Interface in Magnetic Pulse Welded Joints." Materials Science Forum 654-656 (June 2010): 755–58. http://dx.doi.org/10.4028/www.scientific.net/msf.654-656.755.

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Magnetic pulse welding was applied to the lap joining of similar (Al/Al) and dissimilar materials (Al/Fe, Al/Cu, and Al/Ni). The magnetic pulse welding is a kind of impact welding represented by explosive welding. The impact energy is induced by electromagnetic force generated by interaction among discharge pulse, induced magnetic flux, and eddy current produced at the plate surface. The welding was achieved within 10 microseconds with a negligible temperature increase. The welding interface exhibited a characteristic wavy morphology, which was similar to that of the explosive welding. In the Al/Fe, Al/Cu, and Al/Ni joints, an intermediate phase layer was produced along the wavy interface. In order to investigate microstructure of the intermediate phase layer, TEM observation of the welding interface was carried out. TEM observation revealed that the intermediate phase layer consisted of amorphous phase and fine crystal grains.

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41

Lin, Bo, Long Chen, and Dong Hai Cheng. "Microstructure and Mechanical Properties of Electron Beam Welded 5A90 Al-Li Alloy." Advanced Materials Research 1095 (March 2015): 906–10. http://dx.doi.org/10.4028/www.scientific.net/amr.1095.906.

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The microstructure and fracture of electron beam welded 5A90 Al-Li alloy joints were investigated by metallographic microscope and scanning electronic microscope. The results show that the focus of electron beam was on the surface of workpiece when the electron beam focusing current was 1570mA, and the joint formed best. The joints microstructure analysis demonstrated that the weldment mainly consists of fine equiaxed grains which growing coarser with the electron beam current increasing. The tensile strength up to 304.4MPa under the optimal welding parameters (Ua=90KV, If=1570mA, v=25mm/s, Ib=16mA). There were a lager number of dimples on the fracture surface,and the joints obviously present the characteristic of transgranular fracture.

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42

Guedes, Anibal, Ana Maria Pires Pinto, Manuel F. Vieira та Filomena Viana. "Assessing the Influence of Heat Treatments on γ-TiAl Joints". Materials Science Forum 514-516 (травень 2006): 1333–37. http://dx.doi.org/10.4028/www.scientific.net/msf.514-516.1333.

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The heat treatment of γ-TiAl alloy (Ti-47Al-2Cr-2Nb (at.%)) diffusion brazed joints was investigated. Joining was performed using a Ti/Ni/Ti clad-laminated braze alloy foil at 1050 and 1150°C with a dwell time of 10 minutes. The joints were subsequently heat treated at 1250 and 1350°C for 240 and 30 minutes, respectively. The microstructure and the chemical composition of the interfaces were analysed by scanning electron microscopy (SEM) and by energy dispersive X-ray spectroscopy (EDS), respectively. Microhardness tests performed across the interface were used to roughly predict the mechanical behaviour of the as-diffusion brazed and of the heat treated joints. Diffusion brazing produced interfaces with two distinct layers essentially composed of α2-Ti3Al and of TiNiAl; γ-TiAl was also detected for joining at 1150°C. After heat treating, the as-diffusion brazed microstructure of the interface was completely replaced by a mixture essentially composed of γ-TiAl and α2–Ti3Al single phase grains and of (α2 + γ) lamellar grains. Microhardness tests showed that the hardness of the as-diffusion brazed interfaces, which ranges from 567 to 844 HV (15 gf), is significantly higher than that of the titanium aluminide alloy (272 HV). All post-joining heat treatments lowered substantially the hardness of the interface, as the hardness of the main phases detected at the interfacial zone after heat treating the joints is comprised between 296 and 414 HV.

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43

Wei, Ping, Mingfang Wu, Dashuang Liu, Yun Liang, and Ziqiang Zhao. "Face Bend Property of 7N01-T4 Aluminum Alloy MIG Welded Joint by Using Different Welding Wires." Metals 12, no. 5 (May 20, 2022): 873. http://dx.doi.org/10.3390/met12050873.

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7N01-T4 aluminum alloy were welded into three layers by metal inert gas (MIG) welding, with ER5087 welding wire containing Zr and ER5356 welding wire without Zr, respectively. The microstructures and face bend properties of the ER5356 and ER5087 welded joints were investigated. The weld zone (WZ) of the ER5087 welded joint had a smaller grain size than that of the ER5356 welded joint. Two kinds of welded joints were not broken via the face-bend test. However, there were some small holes and microcracks on the surface of the ER5356 welded joint, and there were no obvious defects on the surface of the ER5087 welded joint. The face bending specimen metallography shows that the grains of the cover layer were elongated, and the grains of the bottom layer were extruded. The ER5087 welded joint had a better bending performance than the ER5356 welded joint due to the microstructure refinement of the WZ through adding Zr element in ER5087 welding wire.

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44

Joseph, B., F. Barbier, and M. Aucouturier. "Gravage et pénétration des joints de grains du cuivre par le bismuth liquide." Le Journal de Physique IV 09, PR4 (April 1999): Pr4–235—Pr4–240. http://dx.doi.org/10.1051/jp4:1999431.

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45

Berger, M. H., C. Delamarre, and J. Y. Laval. "Indice de coïncidence des joints de grains dans les céramiques supraconductrices YBa2Cu3O7-x." Revue de Physique Appliquée 25, no. 1 (1990): 35–37. http://dx.doi.org/10.1051/rphysap:0199000250103500.

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46

Zhang, Rui, Yanhong Tian, Chunjin Hang, Baolei Liu, and Chunqing Wang. "Formation mechanism and orientation of Cu3Sn grains in Cu–Sn intermetallic compound joints." Materials Letters 110 (November 2013): 137–40. http://dx.doi.org/10.1016/j.matlet.2013.07.116.

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47

Sylvestre, Julien, and Alexandre Blander. "Large-Scale Correlations in the Orientation of Grains in Lead-Free Solder Joints." Journal of Electronic Materials 37, no. 10 (July 2, 2008): 1618–23. http://dx.doi.org/10.1007/s11664-008-0509-1.

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48

Bocchi, Sara, Gianluca D’Urso, Claudio Giardini, and Giancarlo Maccarini. "Effects of Cooling Conditions on Microstructure and Mechanical Properties of Friction Stir Welded Butt Joints of Different Aluminum Alloys." Applied Sciences 9, no. 23 (November 24, 2019): 5069. http://dx.doi.org/10.3390/app9235069.

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The aim of this work is to evaluate the difference between the properties of several aluminum alloy joints welded with the traditional air-cooled friction stir welding process and others obtained by the combination of the traditional friction stir welding setup with a water-cooling system. In particular, precipitation-hardening alloys AA2024-T3, AA6082-T6 and AA7075-T6, and a work-hardening alloy, AA5754-H111, were taken into account. From Rockwell and Vickers hardness maps, it was possible to observe a clear dependence of the hardness distribution on the cooling systems; joints obtained using a water-cooling system showed higher values of hardness, reached in the central zone and a narrow area interested by the hardness reduction for all the tested alloys. From tensile tests executed orthogonally to the welding direction, it was possible to observe that the alloys have responded differently in terms of ultimate tensile strength and final elongation when the water-cooling system was used. The microstructural analysis of the three precipitation-hardening alloys showed a larger average grain size in the nugget zones for the water-cooled condition. Moreover, in the thermo-mechanically altered zones of the water-cooled AA6082 and AA7075 joints, the grains were characterized by a smaller average size than the grains of the same air-cooled welds.

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49

Babu, K. Tejonadha, S. Muthukumaran, C. H. Bharat Kumar, and C. Sathiya Narayanan. "Improvement in Mechanical and Metallurgical Properties of Friction Stir Welded 6061-T6 Aluminum Alloys through Cryogenic Treatment." Materials Science Forum 969 (August 2019): 490–95. http://dx.doi.org/10.4028/www.scientific.net/msf.969.490.

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An investigation has been made to improve the properties of the friction stir welded (FSW) 6061-T6 aluminum alloys. A cryogenic thermal treatment is developed for the joints during welding and its effects on mechanical and metallurgical properties, and precipitates are evaluated at various welding parameters. The friction stir welded joints with cryogenic treatment attained the better properties than the without cryogenic treatment. The improvement of properties was attributed to the refinement of grain size and to the introduction of a reduction in the softening region of the welded joints. Under cryogenic cooling rates, joints were experienced to the low temperature environments and faster cooling rates, which are contributed to enhance the hardness of the stir zone and heat affected zone regions and the formation of ﬁne grain structure in the stir zone. The results indicated that the formation of finer grains of less than 5 µm in the stir zone, which is smaller than the joints of without cryogenic treatment. Subsequently, mechanical properties drastically improved and the joints achieved a maximum joint efficiency of 74% of the base material

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50

Wen, S., and L. M. Keer. "A Theory of Fatigue: A Physical Approach With Application to Lead-Rich Solder." Journal of Applied Mechanics 69, no. 1 (June 8, 2001): 1–10. http://dx.doi.org/10.1115/1.1412453.

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A fatigue theory with its failure criterion based on physical damage mechanisms is presented for solders. The theory applies Mura’s micromechanical fatigue model to individual grains of the solder structure. By introducing grain orientation (Schmid factor m) into the fatigue formula, an m-N curve at constant loading, similar to a fatigue S-N curve, is suggested for fatigue failure of grains with different orientations. A solder structure is defined as fatigued when the ratio of its failed grains reaches a critical threshold, since at this threshold the failed grains may form a cluster, according to percolation theory. Experimental data for 96.5Pb-3.5Sn (wt. %) solder bulk specimens showed good agreement with the theory and its associated failure criterion. The theory is anisotropic, and there is no size limitation to its application, which could be suitable for anisotropic small-scale (micron scale or smaller) solder joints.

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