Laser Cladding Of Zr-based Amorphous Composite Coatings And Laser-induced Crystallization Of Zr-based Bulk Metallic Glasses

In this paper, Zr-Based amorphous composite coatings were produced by laser cladding on Ti substrate. Microstructure, hardness and tribology characteristics of Zr-based amorphous composite coatings were systematically studied by using OM, SEM, TEM, EDX, XRD, Microhardness and DFPM-type Wear Testing Machines.The composite coatings constitute of amorphous, intermetallic phases and nanocrystalline. The bonding zone between substrate and coating is composed of columnar crystalline of Ti and a -type solid solution(Ti/Zr), which guarantees good metallurgy binding. Due to the presence of hard intermetallic phases, the coatings layer has high micro hardness and low friction coefficient. The predomination wear mechanisms were abrasive, adhesion and desquamate.Under given assumptions, a mathematical model of the transient temperature field during laser crystallization is set up and is analyzed using the finite difference method. Microstructure after crystallization is also studied. Sandwich-like macro structure was found after laser crystallization processing, namely, amorphous layers lie at two sides of the sample, respectively, however the crystalline layers in the middle. The typical morphology of the latter is dendrites crystalline.