Dissertations / Theses on the topic 'Magnesium rare-earth alloys'

Magnesium has the lowest density of any structural metal making it a strong candidate for weight savings in the aerospace and automotive industries. However, strong crystallographic textures combine with anisotropic deformation modes to severely limit formability in wrought magnesium alloys. Recently improved formability has been achieved by the addition of small concentrations of solute rare earth elements which reduce the intensity of recrystallisation textures. Developing a mechanistic understanding of this effect is critical in leading alloy design towards a new class of highly formable wrought magnesium alloys. In this study the static recrystallisation mechanism of rolled magnesium rare earth alloys, which causes the texture weakening, is examined with a particular emphasis on the contrasting texture weakening effects in binary and tertiary magnesium rare earth alloys. In binary magnesium-rare earth alloys the `rare-earth' texture is simply a weakened deformation texture, while recrystallisation of magnesium-zinc-rare earth alloys produces unique `rare-earth' texture components. In the binary alloys weakened recrystallisation textures are attributed to the generation of `off-basal' orientations within regions of high strain localisation during deformation. These orientations recrystallise and subsequently dominate the recrystallised texture. Texture weakening by this mechanism is also thought to be observed in non-rare earth magnesium alloys where dynamic recrystallisation is suppressed by cold rolling. The unique rare-earth texture components in magnesium-zinc-rare earth alloys are found to be determined by the orientation of shear bands in the material. Similarly to texture weakening in the binary alloys, nuclei for these orientations are thought to develop during deformation as a result of strain incompatibilities within shear bands. The mechanism forming these orientations remains unclear, however it is postulated that a complex change in recovery behaviour within shear bands, as a result of rare earth and zinc additions, may be the cause. Retarded dynamic recrystallisation is suggested to be of critical importance in the texture weakening mechanisms of all magnesium alloys, both rare earth and non-rare earth. In rare earth alloys dynamic recrystallisation is suppressed by the segregation of rare earth atoms to grain boundaries. A combination of high resolution TEM and EDX shows rare earth atoms form clusters approximately 2nm in diameter on grain boundaries which are expected to retard dynamic recrystallisation through a solute drag mechanism.

Thesis (M.S.)--University of Missouri--Rolla, 2007.
Vita. The entire thesis text is included in file. Title from title screen of thesis/dissertation PDF file (viewed June 17, 2008) Includes bibliographical references.

The work reported in this thesis demonstrates the potential of the squeeze casting process for the production of castings using magnesium aIloys and its composites. In particular, the studies involving composites are focused on fabrication through squeeze infiltration. These show the ability of the squeeze casting process to produce castings of high metallurgical integrity. The work offers a clear understanding of a number of key parameters for the squeeze casting process which are prerequisites for the production of high strength castings of magnesium aIloys and composites. A better understanding of the behaviour of the squeeze cast material tested at both ambient and elevated temperature has been achieved. A methodology, which aIlows the identification of optimum squeeze casting conditions, has been developed. This has been successfully used in the identification of casting conditions which produce the best tensile properties at both test temperatures. Two casting programmes, namely: primary and secondary programmes, were designed to evaluate the controlling parameters for squeeze cast magnesium alloys and composites. The investigation was conducted with two magnesium alloys: ternary RZ5DF (Mg-4.2o/oZn-RE) alloy and commercial RZ5 (MgZn- RE-Zr) alloy. Different preform systems were investigated during the primary casting programme and the results showed that 14% volume fraction alumina fibres with 5 % silica binder provided the most satisfactory results in terms of ease of fabrication, improvement in strength and cost. Applied pressures of 0.1 to 120 MPa were studied with and without the addition of fibre reinforcement. Pressures of 60 MPa and 80 MPa were found to yield optimum tensile properties in the RZ5DF alloy and its composite respectively. It was also found that a preform temperature of 600°C or above was necessary to achieve minimum resistance to magnesium infiltration at the preform surface. Other process settings, such as applied pressure duration, were also investigated. The influence of pouring and die temperature on the tensile properties was studied during the secondary casting programme. It was found that a higher pouring and intermediate die temperature provided the highest tensile properties. The mechanical properties of castings were tested at both ambient and elevated temperatures. It was found that fibre reinforcement improved the mechanical properties of the materials at ambient temperature but the most significant improvement was observed at 250°C. The effect of grain refinement (zirconium) addition on the squeeze cast magnesium alloys and composites was also investigated. The results indicated that the tensile properties in the zirconium-free RZ5DF alloy were comparable to those of the RZ5 alloy grain refined with zirconium. The influence of zirconium addition on the tensile properties of RZ5DF and RZ5 MMC was similarly reported. Heat treatment improved the properties of the alloys by a small margin and adversely affected the properties of the composite. The overall results showed that there is an opportunity to achieve a significant saving in material and process cost when producing Mg-Zn-RE alloys and composites by the squeeze casting process.

The present study concerns the application of LSM using an excimer laser to enhance the corrosion resistance of rare-earth Elektron 21 magnesium alloy. The alloy has been treated by an excimer laser to produce a highly homogeneous and refined microstructure for improvement of corrosion resistance. The laser surface treatment was applied on two different prepared surfaces of the alloy; i) a ground surface up to 1200 SiC grit; ii) a chemically cleaned surface using CrO3 +AgNO3 boiling solution. The intermetallic phases within the α-matrix that are believed to initiate corrosion have been dissolved by two methods. The first is by the excimer laser, where they were dissolved in the melted layers. The second is by a chemical dissolution prior LSM. Variation of the laser parameters such as changed laser influence (low, medium and high) and increased number of pulses, resulted in formation of thicker melted layers, but promoted the formation of porosity and micro-cracks particularly at overlap regions. The initial stage of this study was aimed at optimising the laser conditions for production of a uniform microstructure, with an increase in the corrosion resistance of the alloy being determined by potentiodynamic polarization measurements in sodium chloride solution. A laser fluence of 6 and 7 J/cm2 with 10, 20, 25, 40 and 50 pulses with a different overlap ratio of 7%, 20% and 50% were subsequently selected as the optimum condition to treat the surface of the alloy. After laser treatment, the top surfaces and the cross-sections of the alloy showed a relatively homogenous melted layer and a significant reduction in the number of large intergranular Mg-Zn-RE phase was achieved resulting in a significant improvement of the corrosion resistance of the alloy. This work also investigated the mechanism of corrosion and the interaction between the intergranular Mg-Zn-RE phase, the Zr-rich regions within the grains and the bulk Mg-rich matrix. The results obtained by scanning electron microscopy (SEM) / energy-dispersive X-ray (EDX) and scanning Kelvin prop forced microscopy (SKPFM) potential map measurements as well as transmission electron microscopy (TEM) / energy-dispersive X-ray (EDX) have shown the importance of the microstructure in the initiation of corrosion in 3.5 wt% NaCl solution, where the Zr-rich regions played a distinct role in the early stages of corrosion in this alloy. However, the obtained results have demonstrated that such laser melted layers improved the corrosion resistance of the alloy, but further work is still needed to obtain the fully understanding of such behaviour which can better the research results, particularly the selectively chemical dissolution of the second phases prior LSM.

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Neste trabalho avaliou-se a ação positiva da substituição de lantânio por praseodímio e de lantânio por magnésio na performance eletroquímica de eletrodos de ligas de armazenamento de hidrogênio em estado bruto de fusão e com tratamento térmico. O La foi substituído por Mg nas ligas La0,7-xMgxPr0,3Al0,3Mn0,4Co0,5Ni3,8 (x=0,0-0,7) e por Pr nas ligas La0,7-yPryMg0,3Al0,3Mn0,4Co0,5Ni3,8 (y=0,0-0,7). Os parâmetros eletroquímicos analisados foram ativação, capacidade de descarga, retenção da capacidade de descarga, autodescarga e alta taxa de descarga. As ligas apresentaram comportamento passivo em relação à corrosão. As análises por MEV/EDS e por DRX com refinamento por Rietveld revelaram a presença majoritária de fases similares às fases LaNi5, PrNi5, LaMg2Ni9 e PrMg2Ni9 em função das composições das ligas estudadas. Os parâmetros de rede e os volumes da célula unitária das fases diminuíram com a substituição crescente de La por Mg e de La por Pr. As capacidades de descarga máxima decresceram com a substituição crescente de La por Mg e de La por Pr, acompanhando o decréscimo da abundância da fase similar à fase LaNi5 e o aumento da abundância da fase similar à fase LaMg2Ni9. Comparativamente, menores taxas de autodescarga e maior estabilidade cíclica foram observadas para o eletrodo da liga na condição x=0,1, ao passo que o eletrodo da liga na condição y=0,0 apresentou maiores valores de alta taxa de descarga, indicando melhor performance cinética.
Tese (Doutorado em Tecnologia Nuclear)
IPEN/D
Instituto de Pesquisas Energéticas e Nucleares - IPEN-CNEN/SP

The effect of individual additions of calcium oxide (CaO), Gd, Nd and Y was investigated on the microstructure, mechanical properties and corrosion resistance of the as-cast ZK40 alloy. The microstructural features were analised using optical, scanning and transmission electron microscopy, X-ray diffraction and Scanning Kelvin Atomic Probe Force Microscopy. The compressive and tensile behaviours of the as-cast alloys at room temperature were investigated. Electrochemical Impedance Spectroscopy, hydrogen evolution and weight loss under immersion in 0.5 wt.% NaCl solution were used to evaluate the corrosion behaviour. The results of the mechanical and corrosion tests were correlated with the microstructures. The 2 wt.% Gd addition enhanced the ductility, while the Nd addition resulted in deterioration in mechanical properties. The addition of 2 wt.% Gd and 1 wt.% Y resulted in the improvement of the ductility. The addition of CaO did not affect the mechanical properties while the 2 wt.% Nd deteriorate it. The 1 wt.% Y addition enhanced the ductility. The CaO addition did not caused enhancement in mechanical properties. The corrosion behaviour was enhanced with the addition of CaO and Gd. The modification of ZK40 with Gd opens up new perspectives in the development of Mg-Zn based alloys.
O efeito da adição individual de óxido de cálcio (CaO), Gd, Nd e Y foi investigado na microestrutura, propriedades mecânicas e resistência à corrosão de ligas ZK40 fundidas. As características microestruturais foram analisadas via microscopia óptica, microscopia eletrônica de varredura, microscopia eletrônica de transmissão, difração de Raios-X e \"Scanning Kelvin Atomic Probe Force Microscopy\". O comportamento à compressão e à tração das ligas à temperatura ambiente foi investigado. Espectroscopia eletroquímica de impedância, evolução de hidrogênio e ensaios de imersão em solução de 0.5% em peso de NaCl foram utilizados para avaliar a resistência à corrosão. Os resultados dos ensaios mecânicos e corrosão foram relacionados com a microestrutura. A adição de 2% em peso de Gd melhorou a ductilidade, ao passo que a adição de Nd resultou na piora das propriedades mecânicas. A adição de 2% em peso de Gd e 1% em peso de Y resultou na melhora da ductilidade. A adição de 1% em peso de Y causou uma melhora na ductilidade e a adição de CaO não teve impacto benéfico nas propriedades mecânicas. A resistência à corrosão foi melhorada com a adição de CaO e Gd. A modificação da liga ZK40 com a adição de Gd abre novas perspectivas no desenvolvimento de ligas Mg-Zn.

Elektron 43 (WE43C) is a modern magnesium rare earth alloy (Mg-RE) with potential light-weighting applications in wrought civil aerospace components. Rare earth elements are known to improve mechanical properties and weaken texture of wrought Mg-RE alloys, but for Elektron 43 the parameters of thermomechanical processing (TMP) that produce optimum microstructure development are not well understood. A large data-set of Elektron 43 flow stress data was collected in an extensive range of hot compression tests at typical TMP temperatures (350-500°C) and strain rates (0.001-100\s). Friction parameters were determined in a ring compression study. Material data was corrected for friction, strain rate and temperature variations. Parameters were fit for a sinh constitutive equation. The corrected material data and used to develop an initial finite element model in the commercial software package QForm. Further work to calibrate the heat transfer parameters is required. The effect of two extrusion parameters (temperature and ram speed) on microstructure and mechanical properties was explored. Extrusion of 60 mm diameter Elektron 43 billets to 20 mm diameter rods (ER=9.92) was conducted at three temperatures (380°C, 420°C and 460°C) and a range of ram speeds (~0.1-15 mm/s). An approximate extrusion limit diagram was formed from empirical relations for extrusion load and hot cracking. Extruded microstructures were bi-modal consisting of dynamically recrystallised (DRX) grains and elongated deformed grains. The typical `prismatic' deformation texture (extrusion direction ED||) was weakened by increasing DRX fraction, concomitant of increased ram speed and temperature. Small DRX grains at low temperature/ram speed had very weak preferences for the 'RE component' with ED||. Increase in ram speed/temperature resulted in a rarely reported 'c-axis' RX texture (ED||) becoming increasingly prominent. This texture dominated at high temperatures and speeds. C-axis grains were larger than those of the RE and prismatic orientations, with the relative difference increasing with DRX fraction. Thus a growth advantage of c-axis grains has been demonstrated: it is postulated these grain boundaries have higher boundary mobility (considering the 90° misoreintation with the deformation texture) and driving pressure (as they are not well oriented for basal slip). Suppression of all RE texture modification followed extrusion at 460°C, 0.16 mm/s. The RX texture was typical of non-RE Mg alloys: ED||. It is argued that at this condition solute segregation is suppressed. Extrusions showed low ambient yield asymmetry. The highest measured yield stresses were correlated with partial RX. These two observations can be explained by a balance of texture, Hall-Petch strengthening and work hardening. One unexplained observation of note is that the maximum observed yields generally correspond to a reversed yield asymmetry.

碩士
國立中央大學
機械工程研究所
96
This research tries to improve corrosion resistance of LAZ1110, LAZ1110 +Be, LAZ1110 +Sc, LAZ1110 +Be +Sc magnesium alloys by means of micro-arc anodizing. In the experiment, the electrolytic solution is composed of 40gl-1 Na2SiO3, 100gl-1 NaOH, 20gl-1 NaPO2and 80gl-1(COOH)2.2H2O in distilled water. After the micro-arc anodizing treatment, it will discuss to various parameters. The results indicated that the anodic oxidation film has better corrosion performance under the pulse current condition. In four materials of LAZ1110, LAZ1110 +Be, LAZ1110 +Sc, LAZ1110 +Be +Sc magnesium alloys, LAZ1110 +Be have the worst of corrosion resistance, and LAZ1110 +Sc have the best of corrosion resistance, in the basic extrapolate, add the Be element have decrease the oxidation on the magnesium alloys surface, this phenomenon destroy the anodic oxidation film of LAZ1110 +Be during micro-arc anodizing treatment, add the Sc element have increase the effect of corrosion resistance. Temperature, frequency, time, current density, duty cycle and electrolytic concentration have an influence on micro-structure and corrosion performance of anodic films. In our research, it fixed current density and another parameter, and it used various of time parameter to find out the best operate condition, the results indicated that at 8min of operate condition of micro-arc anodizing treatment have the best of anodic oxidation film.

博士
國立臺灣大學
材料科學與工程學研究所
95
In this study, the effect of RE content on the microstructure, creep behavior, weld and corrosion properties of Mg-8Al-xRE (x=0, 1, 2 or 3 wt.%) alloys were investigated. The alloys were prepared by melting and casting in a vacuum induction melting furnace in an atmosphere of argon gas. Chemical analysis of the alloys was performed by inductively coupled plasma-atomic emission spectrometer (ICP-AES). To avoid the possible casting defects, such as micro-pore or micro-segregation, the cast ingots were indirect hot extrusion to remove the cast-defects. The microstructural analysis and phase characterizations of alloys were performed by optical microscope (OM), scanning electron microscope (SEM), transmission electron microscope (TEM), and X-ray diffraction (XRD). The fracture surfaces of crept specimens were examined by SEM. Corrosion tests were carried out by potentiodynamic polarization and immersion tests. The study of weld property was accomplished by tungsten-arc inert gas and CO2 laser beam welding. The microstructure analysis, mechanical properties, and corrosion properties of welded specimens were investigated. The microstructure of Mg-8Al alloy with 1-3 wt.% RE additions were conducted: (i) The as-extruded Mg-8Al-xRE alloys consisted of α-Mg matrix, with β (Mg17Al12) and Al11RE3 compounds. (ii) Raising the extent of RE in the alloy also increases the amount and coarsening of the Al11RE3 compounds, but the amount of β phase diminishes and turns into the fine particles. The creep rupture life increment measured at 150℃ is around 40-100 MPa, and the creep rupture life over 150℃ is also prolonged. The marked improvement of the high-temperature tensile creep properties is attributed to the fine rod-like Al11RE3 compound having high thermal stability in the alloys. The stress exponent of the Mg-8Al-xRE alloys is approximately 2, which suggested the creep mechanism of the alloys is controlled by the grain boundary sliding. The creep activation energy of Mg-8Al and Mg-8Al-2RE alloys are 114 and 104 kJ mol-1, respectively. In addition, the aluminum content also has great effects on the creep property of the Mg-Al alloy; when comparing the AZ31-1RE with the Mg-8Al-1RE alloys. The creep resistance of the AZ31-1RE is inferior to that of the Mg-8Al-1RE, as the applied load is high; at either higher or lower test temperature. On the contrary, the creep resistance of the AZ31-1RE is superior to that of the Mg-8Al-1RE, as the applied load is low at any test temperature. Therefore, the effect of aluminum content on the creep properties of Mg-Al alloy is great. The close-grain boundary microstructure of pose-crept Mg-8Al shows that high volume fraction of lamellar β precipitates close-grain boundaries during the creeping. Since the lamellar precipitation occurring during the creeping may effectively multiply the grain boundary area available for easy deformation by grain boundary sliding through the elevated temperature creep. Therefore the creep resistance of Mg-8Al is poor at elevated temperature. Oppositely, no significant change in the microstructure morphology after creep exposure has been observed in the RE-containing alloys. The addition of RE to the Mg-8Al alloy forms the Al11RE3 intermetallic phase, which may suppress the precipitation of lamellar β phase during the creep test. Consequently, the sliding of grain boundaries and the slip of dislocations in the matrix are effectively prevented at elevated temperature, improving the creep resistance of Mg-8Al base alloy. The optimization welding parameters of TIG welding are current 110 A and welding speed 7 m/min. Because the TIG welding has low energy density and high heat input characteristics, the macrostructure of welded Mg-8Al-xRE alloys possess three clearly distinguished regions, including weld metal, heat-affected zone, and parent metal. The aspect ratio of the weld pool is low, about 0.5. Microstructure of weld metal is refined with the increased RE content; and a lot of needle-like or rod-like RE-containing compounds precipitated. The join efficiency is approximate 85%, and the bonding strength is increased with the increasing RE content. However, when the RE content over 2 wt.%, the strength is decreased. The hardness of weld metal is lower than the parent metal, and close to the heat-affected zone. Corrosion rate of the alloy may slightly decrease with the increase of the added RE contents. The corrosion resistance of welded specimens is poor, comparing with the as-extruded alloys. The optimized welding parameters of CO2 laser beam welding are power 2.0 kW and welding speed 2,500 mm/s. The CO2 laser beam welding has high energy density and low heat input characteristics, so the cooling rate of the weld metal is high. The microstructure of the welds is finer than that of TIG welding; and no obviously heat-affected zone is observed, which is due to the laser welded alloys owns fine structure, thus the hardness is higher than that of the TIG welded alloy. In this study, the hardness of the welded metal is slightly lower than that of the parent metal. The aspect ratio of the laser welds is higher than that of the TIG welding, which is about 1.5.

碩士
大葉大學
機械與自動化工程學系
101
In this pursuit of lightness, versatility and recycling generation, magnesium alloys have been increasingly used in products of various fields, which is due to its low specific gravity, high specific strength and specific stiffness, good electromagnetic shielding and high recycling rates, etc. However, due to the nature of great activity, poor electrochemical performance, it is vulnerable to corrode by environment, therefore, appropriate surface treatment is generally required to impart corrosion-prevention function to magnesium metal. In this conversion treatment study, the AZ80A magnesium alloy plate with yttrium element containing as the experimental substrates, and this research divide into two stages. The first stage selects six types of conversion solution which commonly used in industries, under the selected conversion temperature to carry out with different immersion times, and then to observe the surface morphology by SEM and examine the corrosion current density of coating layer. The second stage is to carry out with different drying processes, and investigate the influences of corrosion resistance with drying methods. The first stage experimental results show that the conversion treatment with pH=3.5 manganate solution (nitric acid) for 10 minutes, and pH=9 vanadate solution for 5 minutes have the best corrosion resistance data and adequate coating morphology. It is because that coating completely covered with specimen in a short time, with intense and moderate thickness, also without found crack penetrating into substrate, which is believed to be beneficial to following adhesion processing. The results of second stage experiment (natural shade-drying or oven air-drying) show that all coating layers have relatively flat status without obvious cracks. Only the manganate layer separate out more precipitated phase rich with manganese during oven air-drying processing; believing the precipitated phase may affect the corrosion resistance performance. However, the morphology of vanadate coatings treats with different drying ways showing quite similar, which results in the same corrosion resistance behavior. From a viewpoint of the industrial manufacturing process demand (corrosion resistance and production rate), recommend to use pH=9 vanadate conversion solution for such AZ80A rare earth magnesium alloy, select 60℃with 5 minutes immersion time, and choose the method of 25℃oven air-drying 20 minutes for rapid drying, which should be the best combination of processing parameters. It is believed that can not only effectively improve the production rate, but also maintain the quality and economic benefit.

碩士
大葉大學
醫療器材設計與材料碩士學位學程
104
Consumer demand on products has risen with today’s technological improvement. To adhere to the varying needs, products have evolved from the thick and heavy materials to thin and light materials that are fashionably appealing. To account for environmental protection, material selection and use must exhibit the characteristics of lower pollution and emission, lower power consumption, higher energy efficiency, and high recycle and renewability. Thus, magnesium alloys have become an essential and emergent material. According to industrial needs for fatigue-resistance and light-weight materials. This study applied solid-solution aging treatment in AZ80A extruded magnesium sheet with yttrium (0.25 wt.%) addition, and explored the influence on mechanical and fatigue-resistance properties of this alloy. By applying gas tungsten arc welding, adjusting the aging treatment parameters, and using the S-N curve obtained from fatigue tests, this study determined the optimal aging parameters for predicting the change in durability of such magnesium welds under various stress states. From experimental results show that administering 32 ampere current will completely penetrate the 2.6 mm sheet, and exhibit the optimal welding heat input control. The weld also exist favorable performance in mechanical properties. Thus, this current value was used as the welding current value in subsequent welding for investigating the aging treatment. To examine the microstructure of aged welding sheets revealed that the amount of precipitate increased with increasing aging time, which in turn of enhanced the hardness. The types of precipitate from the aging-treated welds were quite similar. However, differences were observed in shape at different aging times. Under short aging treatment period, the continuous layer-shaped precipitate assisted more evidently in enhancing the tensile strength and hardness of weld. However, it had a detrimental influence on elongation. Rod-shaped precipitates were uniformly precipitated inside the grains with increasing aging time, but these precipitates did not enhance weld strength. In addition, the continuous increase in precipitate negatively affected the elongation. Properties of fatigue resistance were evidently enhanced with increasing the aging time. After aging, the β phase particles exhibited delayed crack growth and hindered dislocation movement. Especially, precipitates obtained with 8 hours treatment evidently enhanced the weld fatigue strength, but those obtained after 16 hours did not and instead exhibited a decreasing trend. Although the mechanical properties and S-N fatigue curve performance were less favorable than those of the original extruded material. However, for applying this type of rare-earth AZ80A alloys to industrials, recommended to use gas tungsten arc welding processes with AC current output should obtain favorable mechanical properties. Regarding post-weld aging treatment, one could apply quenching after 400°C、1 hours solid solution, and followed by aging treatment at 200°C for 8 hours, may effectively enhance weld strength.

碩士
大葉大學
機械與自動化工程學系
101
Due to the highly development of technology, consumers have extended the requests of product from functional oriented to higher quality and light weight property. Also, according to the environmental awareness, the material’s selection, such as reducing pollution emission, improving fuel efficiency and high recycling ratio, are considered to fabricate the products. Therefore, magnesium alloys become the dominant material in new generation. Research was carried out the TIG weld and post-weld heat treatment on yttrium containing AZ80 magnesium alloy plate. By changing the frequency of pulsing current and heat treating parameters, to find the best combination of pulsing frequency and precipitating mechanism enhance the weld quality of this types magnesium alloys. From experimental results shown, with increasing the frequency of pulse current, grain was refined on the fusion zone which will also reveal from the mechanical properties, especially at the frequency of 9 Hz has the best performance than other parameters. Therefore, welds with 9 Hz and 0 Hz frequency were selected to study the difference in the following post-weld aging treatment experiment. Types of precipitates on 0 Hz and 9 Hz aging weld are quite similar. In short aging time, the discontinuous layer-shaped precipitates are able to enhance the hardness and tensile strength of welds, but show inferior influence to elongation. Further increasing the aging time, the short-rod-shaped and mat-shaped precipitates will uniformly precipitate inside the grain, but these precipitates unable to further increase the strength of weld, and the elongation is still decreasing. Based on experimental results, selecting 9 Hz pulse current can obtain better mechanical properties in this rare earth containing AZ80 magnesium alloy TIG weld. For post-weld aging treatment, choosing 400℃- 1 hour for solid solution and following with 200℃- 8 hours for aging treatment, can effectively improve the strength of pulsed weld.