挤压态Mg-3Al-0.8Sr室温压缩过程中的变形行为研究

Deformation behavior of the extruded Mg-3Al-0.8Sr compressed at room temperature

在新三思拉伸实验机CMT-5150上对挤压态Mg-3Al-0.8Sr进行室温压缩实验,研究不同应变量下的组织演变过程,并对压缩时的应力-应变曲线和断口形貌进行分析。结果表明:Sr的加入可以推迟孪生的发生,当应变量超过3.5%时,随着应变量的增加{101-2}拉伸孪晶的数量不断增加;挤压态Mg-3Al-0.8Sr室温压缩时的应力-应变曲线可分为4个阶段并分别对应不同的变形机制。在实验合金的断口形貌图中观察到大量的解理台阶和少量的韧窝,表明实验合金的断裂机制以脆断为主,塑性断裂为辅。

Ambient temperature compression test with CMT-5150 was performed on an extruded round bar of Mg-3Al-0.8Sr alloy. The microstructure evottttion at different strain was investigated. The stress-strain curves and the fracture morphology of the extruded bar compressed at room temperature were also analyzed. The results show that the twinning behaviors are retarded by the addition of Sr. With the increase of compressing strains, the density of twins increases when strain surpasses 3.5%. The stressstrain curves of the compressed alloy can be divided into four stages, which are attributed to different plastic deformation mechanism. A lot of cleavage steps and a few dimples can be observed from fracture morphology, illustrating that the samples compressed at ambient temperature are mainly fractured by brittle mode and supplemented by ductile fracture.