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

This study conducted isothermal compression tests on as-cast 5 vol% (TiB + Y2O3)/alpha-Ti composites at various deformation temperatures ranging from 950-1150 degrees C and strain rates of 10(-3 similar to)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 degrees C, 0.003-0.1 s(-1) and 1090-1140 degrees C, 0.01-0.2 s(-1), and the instability zones were 0.3-1 s(-1), 950-970 degrees C, 0.3-1 s(-1) and 1010-1070 degrees C. After analyzing the thermal deformation behavior of the composites, the microstructure evolution was also investigated. The softening mechanism in (alpha+ beta) phase region is mainly DRV and DRX of alpha phase, while in beta phase region is mainly DRX of beta phase. The reinforcement can impede dislocation movement, thus promoting DRX of the matrix and impeding subsequent grain growth.