An in-situ study on the diffusion growth of intermetallic compounds in the Al–Mg diffusion couple

Abstract

Study on the diffusion growth of intermetallic compounds in the Al–Mg based light-weight metal materials is important due to its close interrelation with property. The current work aims at solving the existing problems of estimating interdiffusivities of intermetallic compounds, such as the early-stage effect on the accurate determination of parabolic growth constant and the simultaneous calculation of composition- and temperature-dependent interdiffusion coefficient. We present the first usage of High-Temperature Laser-Scanning Confocal Microscopy for effective in-situ observation of the time-dependent intermetallic compound growth in the Al–Mg diffusion couples. The method is verified by successfully recording the growth of Al3Mg2 and Al12Mg17 phases in diffusion couples annealed at 380 °C, 400 °C and 420 °C, and the accurate parabolic growth constant of intermetallic compound are estimated without early-stage effect. The experimental data are then subject to a numerical inverse methods to generate a set of self-consistent interdiffusivities, which can reproduce the observed diffusion growth behavior of intermetallic compounds in the Al–Mg diffusion couples. The applicability of current method to other alloy systems is also discussed.