半固态LY11铝合金的组织演变研究

对LY11合金的应变诱发熔化激活法(SIMA)制备工艺进行了研究，定量分析了变形量(ε)、等温温度(Ti)、保温时间(t)等工艺参数和预处理技术对晶粒尺寸、分形维数和晶粒尺寸分布等的影响，讨论了晶粒的大小、形状、尺寸分布的演变规律。结果表明：变形量对晶粒大小、形状的变化影响极大，要获得细小、近球形的晶粒需足够的变形程度；升高等温温度和延长保温时间会促使晶粒长大、球化；所有试样的晶粒尺寸呈正态分布，随着变形量的减小、等温温度的升高和保温时间的延长，峰值点附近晶粒的数目逐渐减小，尺寸逐渐增加；冷、热变形预处理条件对组织演变产生一定的影响，给试样施加变形是SIMA工艺的必要步骤。

Microstructure Evolution of Semi-Solid LY11 Alloy by SIMA

Fabrication of semi-solid LY11 alloy by SIMA (strain-induced melt activation) technique was studied, effects of process parameters, height reduction (), isothermal temperature (Ti) and holding time, on grain size, fractal dimension and grain size distribution were investigated quantitatively. The results show that the height reduction has a great effect on microstructure evolution. Grain growth and spheroidization are promoted with increasing the isothermal temperature or elongating the holding time. Grain size has a Gaussian distribution for all samples. In the adjacent domain of peak point, counts of grains reduced and grain size increased with the decreasing of height reduction, the increasing of isothermal temperature and holding time. Pretreatment condition, i.e. cold or hot deformation, has important effects on microstructure evolution, and deformation of samples is a necessary step in SIMA process.