锥桶式流变成形机制备A356铝合金半固态浆料的研究

Preparation of Semi-solid A356 Aluminum Alloy Slurry by TBR (Taper Barrel Rheomoulding) Technology

采用自主研发的锥桶式流变成形机(TBR),研究了浇注温度、内锥桶转速及剪切温度对A356铝合金半固态组织的影响规律。结果表明,适当降低浇注温度、提高内锥桶转速或降低剪切温度,均有利于获得初生相颗粒细小、圆整、分布均匀的半固态组织;当浇注温度为660℃、内锥桶转速为500r/min、剪切温度为590℃时,获得了理想的半固态浆料,其初生固相颗粒平均直径为41μm,形状因子为0.89;半固态组织的形成受到枝晶破碎和枝晶抑制生长两方面因素的共同影响。

Effects of pouring temperature,rotating velocity of inner barrel and shearing temperature on microstructure of semi-solid A356 aluminum alloy slurry which was prepared by self-developed TBR machine were investigated. The results indicate that it is favorable to obtain semi-solid aluminum alloy slurry structure with fine and spherical solid particles uniformly distributed in the eutectic matrix by reducing pouring temperature,increasing rotating speed of inner barrel or decreasing shearing temperature appropriately. The desirable microstructure of semi-solid A356 aluminum alloy with average primary solid phase diameter of 41 μm and shape factor of 0.89 can be observed with pouring at 660℃ and rotating inner barrel at 500 r/min as well as shearing at 590℃ .The formation of the semi-solid microstructure is controlled by the co-action effects of fragmentation and inhibited growth of dendrite.