무전해코팅법으로 제조한 Al2O3/Ni 나노 Composite의 TEM 미세조직

Abstract

Ni coated Al2O3 composite was successfully prepared by the electroless deposition process. The average size of Ni particles coated on the Al2O3 matrix powder was about 20 nm. It was hard to find any reaction compound as an impurity at interfaces between Al2O3 and Ni particles after sintering. The characterization of microstructure crystal structure and fracture behavior of the sintered body were investigated using XRD, TEM and Vickers hardness tester, and compared with those of the sintered Al2O3 monolithic body. Many dislocations were observed in the Ni phase due to the difference of thermal expansion coefficient between Al2O3 and Ni phase, and no observed microcracks at their Al2O3 and Ni interface. In the Al2O3/Ni composite, the main fracture mode showed a mixed fracture with intergranular and transgranular type having some surface roughness. The fracture toughness was slightly increased due to the plastic deformation mechanism of Ni phase in the Al2O3/Ni composite.