7A60铝合金半固态组织演变及元素分布规律

Microstructure evolution and element distribution of semi-solid 7A60 aluminum

基于形变诱导熔化激活法（SIMA）,采用高压扭转替代传统SIMA中的冷、热塑性变形,制备了具有近球状、细小、均匀颗粒的7A60铝合金半固态坯料;研究了压扭圈数、半固态处理温度和保温时间对半固态坯料微观组织的影响,并通过SEM和能谱线扫描分析了半固态处理温度和保温时间对主要合金元素分布的影响规律。研究结果表明,压扭4圈-6圈,等温温度580℃-600℃,保温20min,可以制备出理想的7A60半固态坯料;随着半固态处理温度的升高或保温时间的延长,基体元素Al和主要强化元素Mg、Zn趋于均匀分布,Cu则逐渐向晶界偏聚;在晶界处偏析的低熔点相主要由Cu构成。

Based on the SIMA method and by replacing the cold and hot plastic deformation of the traditional SIMA with high pressure torsion,the semi-solid billet of 7A60 aluminum alloy with nearly spherical,fine and uniform particles was prepared.The influence of the number of the pressure torsion turns,the semi-solid processing temperature and holding time on the microstructure of semi-solid billet was studied.The influence of the temperature and holding time on the distribution of the main alloy elements was analyzed by SEM and energy spectrum.The research shows that the ideal 7A60 semi-solid billet is prepared under the conditions of pressure torsion 4-6turns,the holding temperature of 580℃-600℃ and the holding time of 20 min.With the increase of the temperature of semi-solid processing and the extension of the holding time,the matrix element of Al and the main strengthening elements of Mg and Zn tend to be evenly distributed,while,the low melting point at the grain boundary segregation is mainly composed of Cu element.