Effect of Strain Rate and Temperature on the Hardness of Cu-TiO۲ Composites Fabricated by Powder Compaction

In the present study, the effects of loading strain rate and processing temperature on the hardness of copper/titanium dioxide (Cu-TiO۲) micro-composites, fabricated via powder metallurgy, were investigated. Specimens were prepared using pure copper powder reinforced with various volume fractions of TiO۲ microparticles (ranging from ۰ to ۱۰%) under three distinct loading conditions: quasi-static (QS), drop hammer (DH), and split-Hopkinson pressure bar (SHB) within a temperature range of ۴۵۰ to ۸۵۰ °C. Experimental results from Vickers microhardness tests indicated that the strain rate has an inverse effect on the final hardness; specifically, samples fabricated at low strain rates (QS) exhibited the highest hardness due to sufficient time for particle rearrangement and the escape of entrapped air. Conversely, increasing the temperature, acting as a thermal activation parameter, led to improved structural integrity and increased hardness across all strain rates by reducing the matrix yield stress and facilitating plastic flow. The findings of this research confirm that by precise control of thermomechanical parameters, structural defects resulting from dynamic loading can be overcome, thereby achieving optimized mechanical properties in metal matrix composites.

کلیدواژه ها:

Powder Metallurgy ، Cu−TiO۲ Composite ، Strain Rate ، Hot Compression ، Vickers Hardness