Design and Fabrication of Functionally Graded Material from Ti to γ-TiAl by Laser Metal Deposition

Abstract

Functionally graded material (FGM) is one kind of advanced material characterized by a gradual change in properties as the position varies. The spatial variation of compositional and microstructure over volume is aimed to control corresponding functional properties. In this research, when 100% γ-TiAl was directly deposited on pure Ti substrate, cracks were formed within the γ-TiAl layer. Then a six-layer crack-free functionally graded material of Ti/TiAl was designed and fabricated by laser metal deposition (LMD) method, with composition changing from pure Ti on one side to 100% γ-TiAl on the other side. The fabricated FGM was characterized for material properties by a variety of techniques. The chemical compositions, microstructure, phases, and hardness of the composite were characterized by Scanning Electronic Microscope (SEM), Optical Microscope (OM), Energy Dispersive X-ray Spectroscopy (EDS), and hardness testing. The microstructure and chemical compositions in different layers were studied.