超声波对AlTiC细化剂的活化机理研究

Effect of high intensitive ultrasound on AlTiC refiner

采用AlTiC作为7050铝合金的细化剂,并在铸造中引入高频超声波,通过比较不同试样表面微观组织的晶粒尺寸以及试样中Ti和C元素的分布等特征,研究超声波对AlTiC细化剂细晶效果的影响及其作用机理.研究结果表明:施加高频超声波能够加速TiAl3相的溶解,提高TiC粒子团与铝溶液的润湿性;粗大晶粒的内部存在一个或多个Ti原子偏聚区;而细小晶粒中Ti原子的偏聚则集中在晶界上,其晶内保持着一个相对较低的质量分数;施加高频超声波能够抑制TiC粒子团间的融合,减小Ti原子偏聚区的面积以及质量分数,进而提高TiC粒子团的形核能力,使所得的金属凝固组织更为细小、均匀.

To study the effect of ultrasound on the refinement of AlTiC grain refiner, the AlTiC was taken as a refiner for 7050 aluminum alloy in the experiments, and was companied by high intensive ultrasound when it was cast. The sizes of the grains and the TiC elements distribution of different samples＇ the microstructure were compared during the nucleation and crystallization process of molten aluminum. The results indicate that ultrasound can accelerate the dissolution of TiAlaphase and im- prove the wettability of TiC particles~ there are one or more of Ti atom segregation in the coarse-cell grain interior; the Ti atom maintains a relatively low concentration in the fine-cell grain, but a segre- gation on the grain boundary; ultrasound can inhibit the fusion of TiC particles group and prevent the formation of mesh Ti atom segregation. For this reason, a finer solidification structure is obtained.