Microscopic morphology and distribution of TiC phase in laser clad NiCrBSiC-TiC layer on titanium alloy substrate

摘要

The microscopic morphology and distribution of TiC phase, as well as its interfaces with a gamma-Ni matrix, in a laser clad NiCrBSiC-TiC layer on a Ti-6Al-4V alloy substrate were characterized using TEM and SEM. The experimental results showed that during laser irradiation heating, TiC particles were partially dissolved into the melted Ni-base alloy, and the dissolved Ti and C atoms were precipitated in the form of TiC dendrites during cooling. The liquid-precipitated TiC particles with smaller sizes are mainly distributed within the gamma-Ni dendrites, while the larger liquid-precipitated TiC and the undissolved TiC particles are located in the regions between the gamma-Ni dendrites. Also, a phenomenon of some TiC particles meeting with each other and merging together was observed in the clad zone. The interfaces of liquid-precipitated TiC phase with the gamma-Ni matrix possess a faceted feature, while the undissolved TiC particles have smooth curved interfaces of a non-faceted type. (C) 2002 Elsevier Science B.V All rights reserved. [References: 24]