Improved mechanical properties of Cu matrix composites reinforced with β-Si3N4 whiskers

Cu matrix composites reinforced with β-Si3N4 whiskers (β-Si3N4w/Cu composites) were prepared by the powder metallurgy method. The results indicated that β-Si3N4 whisker addition and sintering program had significant influence on the densification and mechanical properties of composites. Hardness and bending strength of β-Si3N4w/Cu composites were both improved by a certain amount of β-Si3N4 whisker, although the densification was weakened. The highest hardness and bending strength of β-Si3N4w/Cu composites respectively reached up to 80.9 HRF and 290 MPa. By modifying the crack propagation, the rod-like β-Si3N4 whiskers could improve mechanical properties of composites. Moreover, dislocation strengthening and grain refinement also contributed to the improvement. The high mechanical performance was promoted by the appropriate amount of β-Si3N4 whiskers, while excessive whisker content (>10 vol% for bending strength; >15 vol% for hardness) caused a side effect.