Preparation And Study On Properties Of SiC_p/ZK60 Magnesium Matrix Composites By Solid Phase Recycling

At present, magnesium alloy is the most used metal materials. More than 80% of the magnesium alloy can be recycled. In the process of magnesium alloy products exist large amounts of waste, especially magnesium alloy die casting production. Engaged in magnesium alloy recycling, magnesium resources development, application and regeneration synchronization coordinated development, recycling and reusing of waste, has great significance for resources saving of magnesium industrial.In this work, SiC_p/ZK60 composites was prepared using solid phase recycling method, in which ZK60 served as matrix and SiC particles reacted as reinforcement. SiC_p/ZK60 was conducted by hot extrusion using machined chips. The microstructure, mechanical properties, microhardness and fracture morphology of SiC_p/ZK60 composite were characterized by optical microscope, scanning electron microscope, energy dispersive spectroscopy, micro hardness tester and DNS200 universal material testing machine. The corrosion behavior of SiC_p/ZK.60 composites was investigated by mass loss, electrochemical impedance technique and polarization. The hot compression of SiC_p/ZK60 magnesium matrix composite were performed on Gleeble-1500D at deformation temperature of 360～450℃ and deformation rate of 0.001～1 s-1.The results indicate that the tensile strength and yield strength of SiC_p/ZK60 increases with increasing the volume fraction of SiC particles, and the elongation vice versa. The SiC particles of SiC_p/ZK60 in composite materials occurred broken. It can increase the grain boundary distortion, provide the energy for the recrystallization process, organize grain size refinement. The best amount of adding is of 5%～8% for the grain refining effect. SiC particles can significantly improve the strength of SiC_p/ZK60 composites at room temperature, but bad for plastic. SiC particles in the SiC_p/ZK60 composites are streamlined concentration distribution along the extrusion direction; SiC particles can make SiC_p/ZK60 composite grain size in different degree of refinement.The study of SiC_p/ZK60 composites on corrosion performance show that the SiC_p/ZK60 composites rates with increasing soaking time at first, reduced after the peak when soaking for 24h in the corrosion rate. The corrosion of SiC_p/ZK60 composites is mainly local corrosion in the initial stage of corrosion, having deep pitting corrosion pit with net-like extension. In the corrosion latter stage, the corrosion of SiC_p/ZK60 composites became substrate etching deepened, which leads to the shedding of SiC particles forming hole. The corrosion resistance decreases with the increasing the particle content. Uneven existence of SiC particles, which leads to the uneven distribution of β phase,β phase distribution around the a to corrode, fall off from the β phase; With the increase of corrosion degree, SiC particles fall off. SiC particles have little impact on the anodic dissolution process of SiC_p/ZK60, but can effectively promote the cathodic hydrogen evolution process, accelerated the corrosion process of SiC_p/ZK60. SiC particles is not directly with the ZK60 substrate composition micro thermocouple, but the addition of SiC particles change the microstructure of SiC_p/ZK60 so as to enhance the corrosion rate.The study on hot compressive deformation behavior of SiC_p/ZK60 composites showed that material flow stress depends on the deformation temperature and deformation rate at high temperature compression deformation. When the deformation at a certain constant, flow stress increases with the increase of strain rate; When the strain rate at a certain constant, flow stress decreases with the increase of temperature. Under the experimental conditions, stress index of SiC_p/ZK60 is 3.348, the activation of deformation for 64.970kJ/mol. The model for high temperature compression is ε= 4.49 ×104[sinh(0.051σ)]3.348exp(-64970/RT). SiC_p/ZK60 composites flow stress model of compression deformation, can be described by Zener-Hollomon parameter form, in the strain rate of 0.001～1 s-1 and deformation temperature is 360～450℃ condition.