ABSTRACT

Hot deformation behaviour of as-extruded Mg–5Gd–2.5Nd–0.5Zn–0.5Zr alloy was investigated using compression test at a temperature range of 350–500°C and strain rates of 0.001–1 s⁻¹. Microstructural evolution of cast and homogenised alloy following high-temperature deformation was captured by optical and scanning electron microscopy. Energy dispersive spectrometer results indicated that cast and homogenised samples consisted of eutectic compositions were mainly enriched in Nd and Gd. The flow stress was fairly well fitted by the hyperbolic sine equation where the calculated average activation energy was 297.81 kJ/mol. Hot deformation of the alloy was strongly affected by the high rare-earth metal (RE) constituent, and manifested by twining phenomenon at a temperature below 350°C and by dynamic recrystallization (DRX) and DRX-second phase interaction above 350°C.

摘要

使用压缩试验在 350-500°C 的温度范围和 0.001-1 s ^{-1 的}应变速率下研究了挤压态 Mg-5Gd-2.5Nd-0.5Zn-0.5Zr 合金的热变形行为. 通过光学和扫描电子显微镜捕捉高温变形后铸造和均质合金的显微组织演变。能谱仪结果表明由共晶成分组成的铸造和均质样品主要富含 Nd 和 Gd。流动应力通过双曲正弦方程拟合得很好，其中计算的平均活化能为 297.81 kJ/mol。合金的热变形受到高稀土金属 (RE) 成分的强烈影响，在低于 350°C 的温度下表现为孪晶现象，在高于 350°C 时表现为动态再结晶 (DRX) 和 DRX-第二相相互作用。