自蔓延准热等静压技术制备Ti_3AlC_2可加工陶瓷的压缩性能

Compressive Properties of Ti_3AlC_2 Ceramics Prepared by SHS/PHIP

研究了用自蔓延准热等静压技术制备出的Ti_3AlC_2可加工陶瓷的压缩性能。应变速率为1×10^(-3)/s的实验结果表明:室温(RT)～800℃的压缩断裂方式为脆性断裂,但Ti_3AlC_2陶瓷在RT便已具有显微塑性特征;800～1300℃的压缩行为逐渐表现出塑性特征,且温度越高塑性特征越明显。韧脆转变温度区间(800～1000℃)以上的应力与应变曲线存在着"加工硬化"区域,并且随着温度的升高塑性区域要大于"硬化区"。主裂纹的偏转与分岔、晶粒的分层与扭折是Ti_3AlC_2陶瓷的主要压缩变形机制,而它的塑性变形特征则是位错运动的结果。

The compressive properties of Ti3AlC2 machinable ceramics prepared by SHS/PHIP were tested at different temperature. Stress-strain curves at strain rate of 1×10^-3 s^-1 showed that the compressive behavior was the brittle fracture from room temperature to 800℃, but it presented micro-plastic deformation at room temperature. Compressive behavior of Ti3AlC2 showed plastic deformation form 800℃ to 1300℃. Meanwhile, plastic behavior was found to increase with increasing of the temperature. The brittle-to-ductile transition temperature （BDTT） was between 800℃ and 1000℃. Stress-strain curves above BDTT showed ＂harden area＂, and plastic area was larger than ＂harden area＂ with temperature increasing. Buckling of grains, formation of cavity, branching and deformation of main crack were the important mechanism of deformation in the brittle fracture. Plastic deformation of Ti3AlC2 was related to the motion of dislocation.