Microstructure and mechanical properties of Cu/Al₂O₃ composite prepared by metal injection molding after mechanical alloying

Abstract

10%(volume fraction)Cu/Al2O3 composite was prepared by the process of mechanical alloying and powder injection molding, the effect of alloying time and sintering temperature on microstructure and properties of the composite was investigated, and toughening mechanism of the composite was analyzed. The results show that 10%Cu/Al2O3 composite with good bending strength and fracture toughness can be prepared by the process of mechanical alloying for 10h, degreasing and then sintering at 1550℃. Bending strength and fracture toughness of the composite prepared by this process are up to 532MPa and 4.97MPa·m1/2 respectively. Due to weak diffusion of solid atoms for the composite being sintered below 1550℃, and mobility of particle boundaries being higher than pore escaping rate for the composite being sintered above 1550℃, porosity of the composite increases, and which results in strength and fracture toughness decreasing. Extending alloying time brings grain refinement and strong bonding between Cu and Al2O3 which is beneficial to elevate strength and hardness of the composite, while it is harmful to fracture toughness of the composite. Cu powders dispersing in the Al2O3 matrix protect the Al2O3 grains from coarsening during sintering process. And increasing in toughness of ceramic composite can be attributed to crack bridging and crack deflection when the cracks encounter the ductile Cu.

Keywords

• alumina
• injection molding
• mechanical alloying
• toughening
• composite