Abstract Multiple physical and metallurgical influences exerted by SiC particles (SiCp) still make it difficult to understand that how the addition of SiCp affects the hot tensile deformation behavior of Mg matrix alloy. A deformation mechanism analysis method developed in this study is promising to find a reasonable answer on this problem, via the comparison of SiCp/Mg–5Al–2Ca composite (SiCp/AC52) and Mg–5Al–2Ca alloy (AC52). The effects of SiCp on the constitutive description, deformation mechanism, strain hardening and softening behavior are specially investigated based on the microstructure evolutions, true stress-strain behaviors and fracture characteristics of the uniaxial tensile tests under the deformation temperatures of 290–350 °C and strain rates of 8.3 × 10−4-1.67 × 10−2 s−1. The grains exhibit different growth levels during the hot tensile deformation, and it becomes more evident with the decrease in the strain rate and the increase in the temperature. The addition of SiCp restrains grain growth and leads to a refined and homogeneous grain microstructure. The flow stress at low strain rate is increased with the addition of SiCp, while, which is decreased by SiCp when the strain rate over 8.3 × 10−3 s−1. The addition of SiCp leads to the tress exponent value n and the activation energy value Q increasing from 1.56 and 90.33 kJ/mol to 2.94 and 110.77 kJ/mol, respectively. The dominating deformation mechanism is altered corresponding to the strain rate. The addition of SiCp causes the local stress/strain redistribution, restrains the grain boundary sliding and facilitates the dislocation climb creep in the hot tensile deformation. Moreover, such addition stimulates the generation and coalescence of previously-induced small voids or dimples, while inhibits its extension and enlargement. As a result, the fracture morphologies exhibit an intergranular ductile fracture combined with micro-dimple growth and coalescence.

中文翻译：

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SiC颗粒对Mg-5Al-2Ca合金热拉伸行为及变形机制的影响

摘要 SiC 颗粒（SiCp）所施加的多重物理和冶金影响仍然难以理解SiCp 的添加如何影响Mg 基合金的热拉伸变形行为。通过比较 SiCp/Mg-5Al-2Ca 复合材料 (SiCp/AC52) 和 Mg-5Al-2Ca 合金 (AC52)，本研究开发的变形机制分析方法有望为该问题找到合理的答案。基于290-350°C变形温度下单轴拉伸试验的显微组织演变、真实应力-应变行为和断裂特征，特别研究了SiCp对本构描述、变形机制、应变硬化和软化行为的影响。 8.3 × 10−4-1.67 × 10−2 s−1 的应变率。晶粒在热拉伸变形过程中表现出不同的生长水平，并且随着应变速率的降低和温度的升高变得更加明显。SiCp 的添加抑制了晶粒生长并导致晶粒细化和均匀。低应变率下的流变应力随着 SiCp 的加入而增加，而当应变率超过 8.3 × 10-3 s-1 时，流变应力被 SiCp 降低。添加 SiCp 导致应力指数值 n 和活化能值 Q 分别从 1.56 和 90.33 kJ/mol 增加到 2.94 和 110.77 kJ/mol。主要的变形机制根据应变率而改变。添加 SiCp 导致局部应力/应变重新分布，抑制晶界滑动，促进热拉伸变形中的位错爬升蠕变。此外，这种添加会刺激先前诱导的小空隙或凹坑的产生和合并，同时抑制其扩展和扩大。结果，断口形态表现出粒间韧性断裂与微凹坑生长和聚结相结合。