The effect of modulated matrix microstructure on the deformation behavior in SiC_f/Ti17 composites

摘要

Typical lamellar and equiaxed microstructure of matrix in SiC fiber reinforced Ti17 alloy composites (SiCf/Ti17 composites) can be obtained through matrix composition tuning. The discrepancy of microstructure characteristic results in lower hardness but superior deformation resistance (lower strain-rate sensitivity exponent) in lamellar structure than equiaxed structure. The further microstructure analysis on indent impressions indicates the micro-scale deformation mechanism of lamellar microstructure is principally dominated by dislocation movement in each layer along phase interfaces, rather than in the normal direction due to existence of the large amount of phase interfaces. In contrast, higher hardness comes from dislocation pinning in uniform-distribution grain boundaries in equiaxed microstructure, while quasi-isotropy character makes it more strain-rate sensitivity than lamellar structure. (C) 2019 Elsevier B.V. All rights reserved.