A new method to develop FGM(fuctional gradient materials) by laser beam is suggested, and its properties and characteristics are discussed. In this method, the differences of laser beam absorptance, thermal expansion coefficient, thermal conductivity and solid solubility cause difficulties in making ceramic/metal FGM. Meanwhile, the presence of stepwise compositional profile, the formation of root porosity and oblique crack near boundary region are important in making of metal/metal FGM by laser beam, and some ways to remove these defects are suggested.
As an example, the experimental procedures and results of FGM Inconel/Steel material produced by this method were presented. In this work, the lasersurface-alloying method was applied on steel in order to develop a compositional gradient Cr, Ni/Steel material. Inconel sheet was placed on steel substrate, and then a series of CO2 laser beam was irradiated on surface in order to produce homogeneous alloyed layer. Simultaneous compositional gradients of two different kinds of alloying elements(Cr and Ni) were investigated. Sequential repetition of laser surface-alloying treatments upto 4 times resulted in a fair compositional gradient region with the thickness of about 3 mm from 21% to 0% for Cr, from 40% to 0% for Ni and from 39% to 99% for Fe in this material.