The microstructures of laser alloyed Ni/Ta surface layers.

One of the newer and fastest growing areas in surface metallurgy research is the use of directed energy methods to produce surface alloys of chemical composition very different from their bulk substrates. Here we report the laser induced alloying of Ta films on Ni substrates. Thin alloy regions on Ni, prepared by laser surface alloying (LSA) and studied in our laboratory to date, include Ag, Pd, Sn, Ta [1], Au [1, 2], Co and Zr [3, 4]. We will show that both crystalline and amorphous phases are formed in the laser mixed surface region and that the formation of some of the phases can be understood in terms of the thermophysical and thermodynamic limitations imposed by the choice of Ta and Ni.