Abstract:The interfaces of two materials, Ni/Fe and Cu/Ni, deposited by low pressure plasma spraying method, were studied by means of scanning electron microscopy (SEM) and transmission electron microscopy (TEM) combined with energy dispersive X-ray spectroscopy (EDS). The adhesion between coatings and substrates was measured with the aid of Knoop interfacial indentation testing method. The results show that the interfacial microstructures have strong influence on the mechanical properties. Cu/Ni interface is weak link with NiO amorphous phase. Ni/Fe interfacial layer consists primarily of Fe and Ni oxide crystalline phases, containing dispersive (Fe, Ni) spotlike intermetallic compound phase in nanometer dimension, and the interfacial interdiffusion was detected. The micro-mechanism of interfacial fracture was discussed.

Key words: microstructures; interfacial bonding strength; low-pressure plasma spraying; amorphous phase