The Relationship between Phase Reactions and Dimensional Changes on the Sintering Process of Iron and Tin Mixed Powder Compacts
The effect of tin additions on the sintering process of iron powder compact was investigated by means of dilatometric and microscopic examinations, X-ray diffraction and EPMA. The results were summarized as follows:(1) The first expansion of dilatometric curves from 633 to 773K was caused by penetrating in between iron particles of molten Sn and was analogous to "Copper Growth" in Fe-Cu mixed powder compact.(2) The second expansion from 1013 to 1173K was caused by disappearing of intermetallic compounds and preferentially diffusing of Sn element in iron matrix.(3) Compounds (FeSn2, FeSn, and Fe5Sn3) were formed and disappeared correspondingly with the phase diagram. When heated up to 1223K, Sn element was uniformaly dissolved in the iron matrix.(4) The compact containing larger amount of Sn expanded largely in the first and second expansion region, but shrinked largely at temperatures of 1173K and above because the sinterig was more accelerated in aFe phase than in TFe phase.