晶内型结构的Al_2O_3/SiC_p纳米复相陶瓷

Al_2O_3/SiC_p NANOCOMPOSITES WITH INTRAGRANULAR STRUCTURE

利用非均匀成核的方法在纳米SiC粒子表面包覆一层Al2 O3,通过胶态悬浮液将其均匀分散于Al2 O3 基体中 ,制备出晶内型结构为主的Al2 O3/SiCp 纳米复相陶瓷。通过对材料显微结构及断口形貌分析 ,发现Al2 O3/SiCp 纳米复相陶瓷中 ,含纳米SiC粒子的Al2 O3 晶粒内 ,在残余热应力作用下产生了大量的位错。位错的交截、组合导致微裂纹成核 ,从而诱发材料发生非平面穿晶断裂。

After coating nano_SiC with Al 2O 3 by heterogeneous nucleation processing, nano_SiC particles were uniformly dispersed into Al 2O 3 matrix by mixing them in colloidal suspensions. Consequently, Al 2O 3/SiC p nanocomposites, in which the majority of SiC par _ticles were located in the Al 2O 3 grains, were fabricated. By observation of microstructure of Al 2O 3/SiC p nanocomposites, it is found that the formation of dislocation in the Al 2O 3 grains that contained intragranular SiC was caused by the residual stress. Dislocation crossing and combining lead to form nucleus of microcracks in the Al 2O 3 grains. As a result, non_plane transgranular fracture is induced. The results indicat that the intragranular SiC particles play an important role in changing the fracture mode of the materials.