High temperature tensile fracture characteristics of the oriented TiB whisker reinforced TA15 matrix composites fabricated by pre-sintering and canned extrusion

Abstract

In this paper, the high-temperature (range from 673 K to 973 K with an interval of 100 K) tensile mechanical properties, fracture mechanism and fracture process of the monolithic TA15 alloy and 5 vol% in situ synthesized oriented TiB whisker-reinforced TA15 titanium matrix composites (TiBw/TA15) fabricated by pre-sintering and canned extrusion were investigated. The results showed that the TiBw/TA15 composites fabricated by this method possessed an upper high temperature tensile strength, at the same time, had better high temperature plastic deformation capacity compared to TiCp (TiBw) reinforced TA15 composites fabricated by other methods. TiBw/TA15 showed an obvious improvement in high temperature tensile strength compared to monolithic TA15 alloy while the plasticity was the opposite. The fracture results suggested that TiBw could reinforce the TA15 matrix below 873 K, while the debonding between the matrix and TiBw occurred when the stretching temperature reached 973 K. The presence of micro-pores would not become the source of crack initiation during the tensile process and therefore did not adversely affect the high temperature properties of the composites. With the addition of TiBw, the fracture mechanism was changed to a mixture of brittle fracture and ductile failure (composites) from ductile failure (monolithic TA15 alloy). Additionally, analyzing the different parts of the fracture sample could qualitatively analyze the fracture process of the composites and maybe could replace the in-situ tensile observation at high temperature.