Analysis of tin behaviour on surface of rapidly solidified aluminium alloy powder particles during heating

The behaviour of Sn and Mg at the surface of an aluminium alloy powder particle during heating was investigated by in situ analysis using X-ray photoelectron spectroscopy (XPS). The intensity of the Sn3d photoelectron spectrum increases, according to the increase in the Mg content of the raw particles during heating to 825 K. Sn dissolved in the matrix of the raw particle moves to the particle surface in a liquid state at over 505 K. Sn concentrates at the inner region, which is about 60 nm in the depth from the surface. This phenomenon is independent of the Mg content of the raw particles. However, Mg is necessary for the appearance of Sn in a liquid state at the particle surface during heating because Mg acts to resolute the Al₂O₃ surface film by deoxidisation. The temperature when Sn appears in a liquid state coincides with that of Al in a metallic state after deoxidising the Al₂O₃ surface films. This is between 670 and 700 K.