抄録
It is well known that an abnormal expansion appears in Cu-Sn compacts during sintering. For the purpose of investigating the cause of this phenomenon, author carried out the dilatometric study on kinetics of sintering with Cu-Sn compacts containing about 10% Sn powder and 0.5% Zn-stearate.
Results obtained in this experiment were as follows ; the abnormal expansion appeared always at 798°C, which is the highest peritectic temperature in the Cu-Sn equilibrium diagram, and this expansion increased with increase of heating-rate ; from the microscopic examination, it is presumable that right below the peritectic temperature large amount of liquid phase regions accompanied by the β-phase regions were retained in the compact, however, just at this temperature or above, the β-phase must decompose to the α and liquid phase, subsequently the direct contact with the α-phase accelerates the diffusion of the liquid phase, consequently the liquid phase rapidly disappered above the peritectic temperature on heating ; the absorbed gas in the liquid phase was discharged by rapid solidification at 789°C, showing the dilatometric expansion and the enlarged porosity, judging from the following examination of gas atmosphare, the greater part of the absorbed gas can be estimated as H2.
In order to eliminate the abnormal expansion, slow heating and, isothermal keeping right below the peritectic temperature are recommendable.
