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利用热机械模拟方法详细研究了一种挤压Mg-7.8Li-4.6Zn-0.96Ce-0.85Y-0.30Zr合金的流变行为,温度范围为250～450°C,应变速率在0.001～10 s-1之间。结果表明,该合金的流变应力-应变曲线表现为流变应力先逐渐增加到一个最大值,而后软化。这种流变行为表明在典型的热加工过程中伴随着动态再结晶。该合金的流变应力曲线可以用整个变形温度范围内的双曲正弦函数来拟合。幂指数方程和指数方程并不能很好地拟合应力曲线。双曲正弦方程中的应力指数n很高,而且随着变形温度的增高而逐渐增加。合金的热变形过程主要被位错的攀移所控制。合金的平均热变形激活能Q为148 kJ/mol,高于Mg的自扩散激活能(135 kJ/mol)和点阵扩散激活能(103 kJ/mol)。以上讨论的结果可以归因于合金中稀土元素的加入。
The rheological behavior of a squeezed Mg-7.8Li-4.6Zn-0.96Ce-0.85Y-0.30Zr alloy was investigated in detail using a thermo-mechanical simulation method at a temperature range of 250-450 ° C and a strain rate of 0.001-10 s -1 between. The results show that the flow stress-strain curve of the alloy shows that the flow stress gradually increases to a maximum first, and then softens. This rheological behavior indicates the dynamic recrystallization associated with typical thermal processing. The flow stress curves of this alloy can be fitted with hyperbolic sine functions over the entire deformation temperature range. Exponential and exponential equations do not fit the stress curve well. The stress exponents n in the hyperbolic sine equation are high and increase gradually as the deformation temperature increases. The thermal deformation of the alloy is mainly controlled by the displacement of dislocations. The average activation energy Q of the alloy is 148 kJ / mol, which is higher than the self-diffusion activation energy (135 kJ / mol) and the lattice activation energy (103 kJ / mol) of Mg. The results discussed above can be attributed to the addition of rare earth elements in the alloy.