A rapid route to fabricate in situ TiB-whisker-reinforced Ti-6Al-4V alloy composites by spark plasma sintering and heat treatment

Abstract

In this paper, Ti-6Al-4V matrix composites reinforced with TiB whiskers have been synthesized by spark plasma sintering (SPS) technique and heat treatment (HT). Firstly, the mixed powders were rapidly consolidated via the SPS process at low temperature and high pressure, and then the TiB whiskers were in situ formed during the HT process. The effects of the volume fraction of TiB whiskers on the microstructures and the mechanical properties of the composites were investigated. The results indicate that limited chemical reaction occurred during SPS process. Both density and microhardness of the composites increase with an increase in HT temperature and TiB content. The highest value of relative density (98.4%) and micro-hardness (391 MPa) was obtained in the 3.04 vol% TiB reinforced composites subjected to heat treatment at 1050 °C for 15 min. However, the yield strength of the composites initially increases and then decreases with increasing TiB content, the sample with 2.28 vol% TiB after heat treated at 950 °C for 15 min had the maximum yield strength (1250 MPa). TiB whiskers with high aspect ratio are considered beneficial to strengthening the TC4 alloy matrix. The highest strengthening efficiency induced by grain size refining (Δσrefine) effect and reinforcement’s load-bearing (ΔσTiB) effect reaches up to71.8%.