Papers by Keyword: Boltzmann-Matano Analysis

Abstract: Interdiffusion at 700°C for Ni-22at.%Cr (fcc γ phase) alloys with small additions of Al, Si, Ge, or Pd was examined using solid-to-solid diffusion couples. Rods of Ni-22at.%Cr, Ni- 21at.%Cr-6.2at.%Al, Ni-22at.%Cr-4.0at.%Si, Ni-22at.%Cr-1.6at.%Ge and Ni-22at.%Cr-1.6at.%Pd alloys were cast using arc-melt and homogenized at 900°C for 168 hours. The diffusion couples were assembled with alloy disks in Invar steel jig, encapsulated in Argon after several hydrogen flushes, and annealed at 700°C for 720 hours. Experimental concentration profiles were determined from polished cross-sections by using electron probe microanalysis with pure standards of Ni, Cr, Al, Si, Ge and Pd. Interdiffusion fluxes of individual components were calculated directly from the experimental concentration profiles, and the moments of interdiffusion fluxes were examined to determine average ternary interdiffusion coefficients. Effects of ternary alloying additions on the interdiffusional behavior of Ni-Cr-X alloys at 700°C are presented in the light of the diffusional interactions and the formation of protective Cr2O3 scale.

Abstract: Metal laminates have experienced rapid development in many engineering applications and generally possess enhanced properties with improved service performance. Roll bonding is a major technique used in manufacture of metal laminates. This paper is to investigate the effects of atomic diffusion on the interface development of roll bonded metal laminates in the sintering heat treatment process. Copper/aluminium bi-metal laminates were prepared by roll bonding at 430oC with a 40% rolling reduction in a single pass. Sintering was then applied at 450oC for various periods. It was found that multi-phase interfacial layers developed in the sintering process and shifted towards the aluminium metal with increasing sintering time. Composition profiles of the metallic elements were carefully determined across the interfacial area of the bonded material. Interdiffusion coefficients of the metallic elements were determined using Boltzmann-Matano analysis. The results were correlated with the multi-phase development in the interfacial area.