Strength and plastic flow in “in situ” TiC reinforced aluminum composites

Abstract

The deformation behavior of TiC particulate-reinforced aluminum composites (Al-TiCp) was investigated in this work using pure aluminum as the reference matrix material. Uniaxial compression tests were carried out at 293 and 623 K and at two strain rates (3.7×10−4 and 3.7×10−3 s−1). Yield strengths of up to 127 MPa were found in composites containing 10 vol pct TiC particulates, which were almost 4 times the yield strength of pure Al. In addition, at 623 K, relatively small reductions in yield strength were found, suggesting that this property was rather insensitive to temperature for the temperatures investigated in this work. Nevertheless, at 623 K, increasing the rate of straining from 3.7×10−4 s−1 to 3.7×10−3 s−1 lowered the yield strength, particularly in 10 vol pct TiCp-Al composites. Two stages of work hardening were identified in pure Al and a 10 vol pct TiCp composite during plastic flow through the modified version of the Hollomon equation (σ = Kɛn ± Δ). In particular, the work-hardening exponents found in pure Al shifted from high to low values as the extent of plastic strain was increased while the opposite was true for the 10 vol pct TiCp composite. Finally, at 623 K, dynamic recovery mechanisms became dominant at plastic strain levels >0.2 in 10 vol pct TiCp-Al composites, with the effect being minor at room temperature.