Effect of sintering temperature on the microstructure and properties of Al–7.5Cu–1Si alloy

Abstract

With increasing requirements for environmental protection and energy conservation, Al–Cu powder alloys play an important role in machine weight reduction. During the preparation of the Al–Cu powder alloy, an appropriate sintering temperature helps improve the comprehensive performance of the alloys. In this study, powder metallurgy was used to prepare Al–7.5Cu–1Si alloys, and the effects of different sintering temperatures on their relative sintering density, hardness, and tensile strength were studied. The microstructure and phase composition of the alloy were observed and analyzed by scanning electron microscopy and x-ray diffraction, and the mechanical properties of the alloy were studied using a Brinell hardness tester and a universal material testing machine. By analyzing the microstructural changes of the alloys at different sintering temperatures, the optimal sintering temperature of the alloy was determined to obtain the best properties. The results demonstrated that the sintering temperature significantly affected the diffusion and migration of the metal particles inside the alloy. When the temperature was low, numerous pores were present in the alloy, and the degree of bonding between the metal particles was poor. As the temperature increased, the number of pores in the alloy decreased, and good metallurgical bonding occurred between the particles. The relative densities and mechanical properties of the alloys were significantly affected by the sintering temperature. When the temperature was below 570 °C, the relative density and mechanical properties were low. At 590 °C, the alloy underwent deformation and was in an over-sintered state. The best sintering temperature was 570 °C. This is because at this temperature, the relative sintering density, hardness, and tensile strength of the alloy all reached maximum values, which were 98.6%, 71 HB, and 153 MPa, respectively.