原位合成TiB和TiC增强钛基复合材料的超塑变形力学行为

Mechanical Property of Superplastic Deformation of in-situ Synthesized (TiB+TiC)/Ti Matrix Composite

研究了利用普通熔铸设备,原位合成法制备的TiB和TiC颗粒增强钛基复合材料的高温变形行为.在915～1100°C,初始应变速率ε=10-2～10-4s-1,进行了超塑拉伸实验.结果表明,在1015°C、ε=10-2s-1时,延伸率最大,为235%,相应的应变速率敏感性因子为0.22,最大的m值并不对应最大的延伸率.计算得到各温度下的超塑变形表观激活能为144～311kJ/mol,激活能的差异表明,该复合材料的高温变形在不同温度下受不同机制控制.同时,利用扫描电镜观察了断口形貌,分析了其变形机理.

High temperature deformation behavior of in-situ synthesized (TiB + TiC)/Ti matrix composite by common casting equipments was studied. Superplastic tension tests under conditions 915-1100°C and initial strain rates ranging 10-2-10-4s-1 were carried out. It is indicated that a maximum elongation of 235% and m value of 0.22 are recorded at a strain rate of 10-2s-1 at 1015°C, but the maximum m and the maximum elongation do not correspond each other under the same condition. The activation energy is determined to be 144-311 kJ/mol at different temperatures. The activation energy difference indicates that the high temperature deformation of the composite is controlled by different mechanism at different temperatures. The fracture surfaces of the composite were investigated by means of SEM in order to analyze deformation mechanism.