Microstructure evolution mechanism of micron particle reinforced magnesium matrix composite at room temperature

In this paper, the micron SiCp/AZ91 composite fabricated by stir casting is forged at 420 degrees C with 50% reduction initially, and then subjected to extrusion at 370 degrees C with the ratio of 16. Microstructure evolution of magnesium alloy containing micron particles during room temperature tensile process has been investigated using transmission electron microscopy. Results illustrate that the micron particles lead to inhomogeneous deformation of magnesium matrix, thus causes dislocation pile-up near particles and the formation of twinning away from particles. Larger stress concentration occurs at the end of some micron particles, which results in the appearance of microcracks. In the course of subsequent deformation, the composite fractures due to rapid extension of microcracks. (C) 2012 Elsevier B.V. All rights reserved.

本文中，采用搅拌铸造法制备的微米SiCp/AZ91复合材料首先在420℃下进行50%变形量的锻造，然后在370℃下以16的挤压比进行挤压。利用透射电子显微镜研究了含微米颗粒的镁合金在室温拉伸过程中的微观结构演变。结果表明，微米颗粒导致镁基体变形不均匀，从而在颗粒附近引起位错堆积，并在远离颗粒处形成孪晶。一些微米颗粒端部出现较大的应力集中，导致微裂纹的产生。在后续变形过程中，由于微裂纹的快速扩展，复合材料发生断裂。（C）2012爱思唯尔有限公司。保留所有权利。