Construction of Process Map and microstructure evolution of 5 vol.% (TiB + Y2O3)/α-Ti composites under isothermal compression

Abstract

This study conducted isothermal compression tests on as-cast 5 vol% (TiB + Y2O3)/α-Ti composites at various deformation temperatures ranging from 950–1150 °C and strain rates of 10−3∼1.0 s−1. The corresponding thermal deformation activation energy and the constitutive equations were derived from the stress-strain curves of the different phase regions. Then the Process Map of the composites was constructed and the regions of prone plastic processing were obtained as 950–1020 °C, 0.003–0.1 s−1 and 1090–1140 °C, 0.01–0.2 s−1, and the instability zones were 0.3–1 s−1, 950–970 °C, 0.3–1 s−1 and 1010–1070 °C. After analyzing the thermal deformation behavior of the composites, the microstructure evolution was also investigated. The softening mechanism in (α + β) phase region is mainly DRV and DRX of α phase, while in β phase region is mainly DRX of β phase. The reinforcement can impede dislocation movement, thus promoting DRX of the matrix and impeding subsequent grain growth.