Microstructure of TiC dendrites reinforced titanium matrix composite layer by laser cladding

摘要

In previously reported work [1-7] high-power lasers were used to produce TiC reinforced titanium matrix composite layer. Ayers et al. [1,2] injected TiC into the laser-melted zone of Ti-6Al-4V alloy, leading to an increase in the hardness to about 460 H_v. Partial solution of TiC particles occurred under the laser radiation, and TiC dendrites formed during solidification. Walker et al. [3] obtained a high-content TiC clad layer on the surface of Ti substrates by pre-coating with graphite before laser melting. A method of laser melting the mixture powders of titanium and graphite was used to prepare TiC/Ti composite layer [4]. Man et al. [5] chose Cr_3C_2 and Ti powders as the starting materials, and obtained an in-situ synthesized TiC/Ti composite layer on Ti-6Al-4V by laser cladding. In the process of laser cladding on Ti-6Al-4V alloy with TiC and TiC+NiCrBSi powders, the TiC particles were melted and then solidified to form dendrites in TiC clad layer and form fine spherical particles and dendrites in TiC+NiCrBSi clad layer respectively [6,7].