Some aspects on work hardening behaviour of Cu-5%SiC powder composites

The work hardening behaviour of cold upsetting of Cu-5%SiC powder preforms have been compacted and sintered from electrolytic copper powder is presented here. Cu-SiC Powder Metallurgy preforms having initial theoretical density of 85%, with four initial aspect ratios, namely 0.40, 0.50, 0.60 and 0.70 were prepared using a suitable die-set assembly on a 1.0MN UTM. Sintering operation was carried in an electric muffle furnace at the temperature of 850±10°C for a holding period of an hour. Experiments were conducted and measurements were recorded on the development of barreling and strain variations at the free surface with zinc stearate as lubricant. The instantaneous strain hardening exponent n_i and strength coefficient k_i of the Cu-SiC preforms were calculated and found to reach the peak value when packing density is at low value. Further, it has been observed that the value of n_i and k_i decreased and found to be fluctuating as the axial strain value of the fractional density value increased. It has further been established that the initial geometry of the P/M preforms played a significant role in influencing both n_i and k_i values.