THE BINARY-SYSTEM PT-SN

The system Pt-Sn was completely revised over narrow intervals of compo sition (1-2 at.% Sn), using more than 60 carefully annealed alloys (mo re than 3000 h at T>600 degrees C), measured with differential thermal analysis, X-ray diffraction and electron microprobe analysis. The fiv e stoichiometric intermediate phases have generally higher melting poi nts than previously indicated in the literature for Pt3Sn (1402 degree s C) and PtSn (1276 degrees C) and higher peritectic decomposition tem peratures for Pt2Sn3 (898 degrees C), PtSn2 (748 degrees C) and PtSn4 (540 degrees C). The intermediate phase PtSn has a structure similar t o PtSn3 (P6(3)/mmc), with a strictly stoichiometric composition as sho wn by electron microprobe and X-ray diffraction methods. The lattice p arameters of all intermediate phases in the binary system PtSn have be en calculated, showing no detectable variations due to composition. Th e solubility of platinum in tin is negligible.