Phase Transition, Microstructure Evolution and Tribological Behaviour of a Laser Clad NiAl Intermetallic Compound Coating at Elevated Temperatures
Y-J. Yu, J-S. Zhou, J-M. Chen, H-D. Zhou, C. Guo and L-B. Yang
Phase transition, microstructure evolution and tribological behaviour of a laser clad single phase NiAl coating induced by heating at 800°C was investigated by means of X-ray diffraction (XRD), scanning electron microscopy (SEM) and high resolution transmission electron microscopy (TEM). It was found that the Ni3Al phase precipitated along NiAl grain boundaries, showing a fine strip and netlike dendrite microstructure via the solid-state diffusion of Ni atoms during heating process. NiAl and Ni3Al phases had a common <110> zone axis. The results of friction and wear explicated that Ni3Al phase was beneficial to refine the microstructure and hence improved the mechanical properties and high-temperature wear resistance of the NiAl coating. Phase transition and microstructure evolution of NiAl intermetallic compound coating during heating process acquire well understand the diffusion behaviour of NiAl and provide better guidance on its production and practical use.
Keywords: NiAl, intermetallics, laser processing, phase transition, microstructure evolution, tribological behaviour