Strain rate influence on mechanical behaviour of Ti-6Al-4V reinforced with TiC or TiB composites produced by sintering and hot isostatic pressure on compression

Layered metal-matrix composites were produced via Blended Elemental Powder Metallurgy, followed by hot isostatic pressing (HIP). Two three-layer samples were fabricated, consisting of a matrix based on the Ti-6Al-V (wt.%) (Ti-64) alloy. Each layer/tile was synthesized using BEPM and reinforced with 10, 20, or 40 vol.% TiC or TiB particles. The use of HIP effectively bonded individual MMC tiles into cohesive, dense three-layer samples, thereby nearly eliminating residual porosity. Quasi-static compression tests were performed at strain rates of 10 -3 s -1 and 10 -1 s -1 . Dynamic tests were conducted using the split Hopkinson pressure bar method, with strain rates ranging from approximately 2500 s -1 to 4600 s -1 . For MMC with TiC, these features are associated with the formation of large conglomerates of carbide-phase particles at the synthesis stage and during long-term isothermal holding under load during HIP. During compression testing, the primary deformation localizes within TiC particles, causing their fragmentation and the subsequent destruction of the matrix-phase bridges between them. In MMC with TiB, the strengthening particles are more dispersed, and relatively coarser residues of untransformed TiB2 particles and dispersed titanium monoboride particles coexist, arising from the interaction of diboride with the titanium matrix. The enhanced resistance to destruction at higher strain rates in MMCs strengthened with TiB2 and TiB is attributed to their more homogeneous dispersion compared with MMCs strengthened with TiC.