DISSOLUTION RATE MEASUREMENTS OF TIN IN TI-6242

This paper describes measurements of the dissolution rate of nitrided Ti sponge and monolithic TiN rod in molten Ti-6242. The dissolution ra te is described in terms of an interface recession rate that was 2.2 m u m/s for a Ti-6242 temperature of 1725 degrees C and dissolution time s between 1 and 100 min. Similar dissolution rates were measured for n itrided sponge and monolithic rod. This report also describes the micr ostructural and chemical interdiffusion phenomena that occur during di ssolution of solid delta TiN in molten Ti-6242. There is a N-containin g solid alpha Ti layer and a N-solidified beta Ti layer between the so lid delta TiN and liquid Ti-6242 during dissolution. Microprobe measur ements indicate that diffusion of Al, Zr, Sn and Mo into delta TiN did not occur. Steep N concentration profiles were observed in the alpha Ti layer. Al, Zr, Sn and Mo were observed in the N-solidified beta Ti layer, but their concentrations were depleted with respect to Ti-6242. The N-solidified beta Ti layer contained <1% N. Similar microstructur al and interdiffusional behaviors were observed during dissolution of nitrided sponge and monolithic delta TiN rod in molten Ti-6242. Copyri ght (C) 1996 Acta Metallurgica Inc.