Development of ultrahigh-strength low-alloy Mg-0.7Al-0.3Ca-0.4Mn (wt.%) alloy with excellent ductility via controlling extrusion temperature
Development of ultrahigh-strength low-alloy Mg-0.7Al-0.3Ca-0.4Mn (wt.%) alloy with excellent ductility via controlling extrusion temperature
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DOI：
10.1016/j.jmrt.2023.05.275
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发表时间：
2023-06
期刊：
影响因子：
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通讯作者：
Xiaoqing Liu;X. Qiao;Yuwei Liu;R. Pei;Xianke Zhang;Lin Yuan;Y. Chi;Xiurong Zhu;Mengmeng Yu-Mengm
中科院分区：
文献类型：
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作者：
Xiaoqing Liu;X. Qiao;Yuwei Liu;R. Pei;Xianke Zhang;Lin Yuan;Y. Chi;Xiurong Zhu;Mengmeng Yu-Mengm
对Mg-0.7Al-0.3Ca-0.4Mn （AXM070304, wt.%）合金进行挤压，挤压速度为1 mm/s，挤压比为25:1。挤出温度范围为170℃~ 400℃。系统探讨了挤压温度对稀释型AXM070304合金显微组织和力学性能的影响。随着挤压温度的升高，动态再结晶（DRXed）晶粒的平均尺寸增大，而基纤维织构强度减小。当挤压温度从170℃升高到400℃时，低合金AXM070304挤压合金的抗拉屈服强度（YS）从437 MPa降低到246 MPa，而失效伸长率（EL）从2.9提高到16.9%。该合金在200℃下挤压得到412 MPa的抗拉强度、418 MPa的极限抗拉强度和14.8%的EL，具有良好的延展性和超高强度。超高能谱主要是由溶质Al和Ca原子晶界偏析的超细再结晶晶粒（0.61 μm）强化引起的。Al原子和Ca原子的共偏析、晶界处的纳米Al2Ca和β-Mn颗粒相抑制了DRXed晶粒的生长。超细晶AXM070304合金在拉伸载荷作用下发生塑性失稳，这可能是由于Al原子和Ca原子的晶界偏析需要高能量垒来发射位错所致。当拉伸应力达到峰值时，可动位错密度突然增大。
Mg-0.7Al-0.3Ca-0.4Mn (AXM070304, wt.%) alloy was subjected to extrusion with a ram speed of 1 mm/s and an extrusion ratio of 25:1. The extrusion temperature varies from 170 °C to 400 °C. The influence of extrusion temperature on microstructure and mechanical properties of the dilute AXM070304 alloy was systematically explored. With raising the extrusion temperature, the average size of the dynamic recrystallized (DRXed) grains was increased, while the intensity of the basal fiber texture was decreased. When the extrusion temperature was escalated from 170 °C to 400 °C, the tensile yield strength (YS) of the low-alloy AXM070304 extrusion alloy was decreased from 437 to 246 MPa, while the elongation to failure (EL) was increased from 2.9 to 16.9%. The alloy extruded at 200 °C obtains an YS of 412 MPa, an ultimate tensile strength (UTS) of 418 MPa and an EL of 14.8%, exhibiting excellent ductility and ultrahigh strength. The ultrahigh YS was mainly due to the strengthening from ultra-fine recrystallized grains (0.61 μm) with grain boundary segregation of solute Al and Ca atoms. The growth of DRXed grains was inhibited mainly by the co-segregation of Al atoms and Ca atoms, nanosized Al2Ca and β-Mn particle phases at the grain boundaries. Plastic instability occurred under tensile loading in the ultrafine-grained AXM070304 alloy, which may be due to the fact that the grain boundary segregation of Al atoms and Ca atoms requires a high energy barrier for dislocation emission. Once the tensile stress reaches the peak value, the mobile dislocation density increases suddenly.