Abstract
Abstract This paper takes nano-SiCp/Al–7Si matrix composites prepared by powder metallurgy as the research object. With the help of advanced microstructure characterization techniques and performance analysis methods, the effect of nano-SiCp volume fraction on the microstructure and properties of composites is systematically studied. Based on optimizing the volume fraction of nano-SiCp, the thermal deformation behavior of the composites is investigated. It was found that with an increase of nano-SiCp content, the distribution uniformity of nano-SiCp decreases gradually. And because the surface of nano-SiCp is easy to adsorb gas and the aggregated distribution of nano-SiCp is not conducive to the sintering process, the density of the composites shows a gradually decreasing trend. The hardness of the composites tends increasing gradually, and the increase in amplitude gradually decreases. Due to the addition of nano-SiCp, there are many interfaces between SiCp and Al matrix, and cracks are prone to initiation and expansion at the interface. Therefore, as the volume fraction of nano-SiCp increases, the elongation of nano-SiCp/Al–7Si composites gradually decreases. When the volume fraction of nano-SiCp is 2%, the strength of the composites reaches the maximum value of 217 MPa. Compared with the Al–Si alloy without adding nano-SiCp, the results increased by 37.3%. In addition, with the decrease of strain rate and the increase of deformation temperature, the dislocation density in the composites gradually decreases, and the dynamic softening progresses more fully. The dynamic recrystallization nucleation mechanism mainly includes the subcrystal merging mechanism and the grain boundary bowing mechanism.
Highlights
With the rapid development of modern industry, the traditional single metal material has been far from meeting the requirements of modern industry on the performance of materials, so metal matrix composites came into being [1,2]
This may be because the preparation temperature required by the powder metallurgy method is lower than that of the casting method, and the silicon phase is not generated by heterogeneous nucleation with nano-SiCp as the substrate in the liquid phase
When the content of SiCp is 2%, the strength of the composites reaches the maximum value of 217 MPa and the results increased by 37.3% when compared with the Al–Si alloy without adding nano-SiCp
Summary
With the rapid development of modern industry, the traditional single metal material has been far from meeting the requirements of modern industry on the performance of materials, so metal matrix composites came into being [1,2]. Among many metal matrix composites, SiCp/Al composites are widely used in aerospace, electronic packaging, and automobile fields because of their low thermal expansion coefficient, high strength, good wear resistance, and other advantages [3,4,5]. Mao et al [6] prepared aluminum matrix composites (AMCs) with SiCp volume fractions of 2.5 and 5% by powder metallurgy and studied the effect of SiCp volume fraction on microstructure and properties of composites. The results show that with the increase of SiCp volume fraction, the grain size of the composites decreases, the dislocation strengthening increases, and the strength and hardness are significantly improved. This study indicated that, with the increase of SiCp size, the SiCp distributed more uniformly in the matrix and the coefficient of thermal expansion of composites increased, but the tensile strength of composites decreased. The addition of micron-sized SiCp to the matrix material can achieve a significant strengthening effect, a large number of studies have shown that the micron-sized SiCp can significantly reduce the plasticity of the matrix material while strengthening the matrix material, so that the application of SiCp/Al composites in the industrial field is limited [8,9]
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