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研究了热挤压态Mg-3Al-3Zn-1Ti-0.6RE镁合金的高温拉伸变形行为和微观组织演变,分析了该合金在温度为623~723 K,应变速率为10~(-4)~10~(-2) s~(-1)条件下的流变应力随温度和应变速率的变化,归纳了温度、应变速率与流变应力的关系。研究结果表明:温度和应变速率是影响流变应力的主要因素,在变形过程中,流变应力随变形温度的升高和应变速率的降低而减小。在本实验条件下,该合金的变形本构方程可用双曲正弦函数ε=A[sinh(ɑσ)]~nexp(-Q/RT)来描述,应力指数n=3.286,激活能Q=238 k J/mol,表明该合金的高温塑性变形机制主要是位错滑移和攀移。
The tensile deformation behavior and microstructure evolution of hot-pressed Mg-3Al-3Zn-1Ti-0.6RE magnesium alloy were investigated. The results show that the alloy has better mechanical properties at 623 ~ 723 K and strain rate of 10 ~ (-4) The relationship between temperature and strain rate and flow stress was summarized with the change of temperature and strain rate under ~ 10 ~ (-2) s ~ (-1) condition. The results show that temperature and strain rate are the main factors affecting the flow stress. During the deformation, the flow stress decreases with the increase of deformation temperature and the decrease of strain rate. Under this experimental condition, the deformation constitutive equation of the alloy can be described by the hyperbolic sine function ε = A [sinh (ɑσ)] ~ nexp (-Q / RT). The stress exponent n = 3.286 and the activation energy Q = 238 k J / mol, indicating that the high temperature plastic deformation mechanism of the alloy is mainly dislocation slip and climbing.