强制对流搅拌制备铝合金半固态浆料及其组织演变

摘要

A356 aluminum alloy semisolid slurry was prepared by self­developed forced convection rheoforming machine (FCR). The effects of barrel temperature, pouring temperature and rotation speed on the microstructure of semisolid slurry were investigated. The solidification behavior of the semisolid slurry preparation was discussed. The results show that reducing the barrel temperature and pouring temperature and increasing the rotation speed appropriately are beneficial to obtain semisolid slurry with fine and spherical solid particles distributed in the matrix uniformly. The desirable semisolid slurry with average primary solid phase diameter of below 80μm and shape factor of above 0.75 can be obtained at pouring temperature of 620-630℃, barrel temperature of 570-580℃and rotation speed over 200 r/min. The FCR device can greatly change the situation that the melt relies on diffusion to transfer the heat and mass in traditional solidification conditions. It destroys the generation environment of dendrites. The temperature field and the composition of the melt are going uniformly, which will be advantage to obtain better semisolid microstructure.%采用自主研发的强制对流搅拌装置(FCR)，研究筒体温度、浇注温度和搅拌速度对A356铝合金半固态组织的影响规律，探讨半固态浆料制备过程中的凝固行为。结果表明：适当降低浇注温度、筒体温度和提高搅拌速度均有利于半固态浆料组织的改善，能够制备晶粒细小、圆整、分布均匀的半固态组织；当浇注温度为620~630℃、筒体温度为570~580℃、筒体转速为200 r/min以上时，均能获得理想的半固态浆料，其初生固相颗粒平均直径在80μm以下，形状因子在0.75以上；强制对流搅拌装置极大地改变了传统凝固条件下熔体依靠传导单向传热和扩散缓慢传质的状态，使熔体的温度场和成分场趋于一致，破坏了枝晶生长的条件，有利于获得较好的半固态组织。