TiB_2颗粒对7075铝合金流变成形显微组织的影响

Effect of TiB_2 particle on microstructure of 7075 Al alloy in rheological forming

采用原位反应制得纯净的Ti B2/7075复合材料,并经保温弯通道挤压成形制备半固态Ti B2/7075复合材料。研究结果表明:随着颗粒质量分数的增加,原位反应放热量增加,生成Ti B2颗粒粒径减小;在增强颗粒、冲刷搅拌和对流的共同作用下,熔体迅速形核并球化;670℃的熔体经三弯石墨通道流变挤压成形,颗粒质量分数为3%时,7075铝合金晶粒尺寸达到32.09μm,形状因子为0.85;颗粒含量为4.5%时,晶粒尺寸达到23.90μm,形状因子为0.96;颗粒含量为6%时,晶粒尺寸达到29.98μm,形状因子为0.95。

Novel reactive technique was employed in the synthesis of 7075 Al matrix composites, and TiB2/7075 semi-solid composites were prepared by extruding technology after flowed through serpentine graphite channel. The results show that the more the heat quantity is created, when the TiB2 particle size is small, the mass fraction of particles in-situ reaction increases. The combination of particles, scouring and convection lead to nucleating and globurizing of the grain. After the extruding forming with three curved channels of molten at 670 ℃, the mean grain sizes and shape factors of the 3% TiB2/7075 composite are 32.09 μm and 0.85. The mean grain sizes and shape factors of 4.5% TiB2/7075 composite are 23.90 μm and 0.96 respectively, and those of 6% TiB2/7075 composite are 29.98 μm and 0.95 respectively.