Local Appearance of Sn Liquid Phase at Surface of Aluminum Alloy Powder during Heating

Local appearance of Tin (Sn) liquid phase at the surface of rapidly solidified aluminum alloy particles including Mg and Sn was investigated by X-ray Photoelectron Spectroscopy (XPS) and Auger Electron Spectroscopy (AES). Sn3d photoelectron spectrum intensity gradually increased with increasing the Mg content of raw particles during heating up to 825K. AES analysis indicated that supersaturated Sn atoms by rapid solidification diffused to the particle surface in a liquid state at elevated temperature over 505K, and finally concentrated at the inner region of about 50~60 nm in depth from the topmost surface. Mg was, however, necessary for this phenomenon, because it was effective for the chemical breakage of aluminum oxide films at the particle surface by the deoxidization reaction from 670K to 700K