射出成形を利用したＦｅ‐Ｎｉ合金焼結体の機械的性質に及ぼす脱バインダ条件の影響

Abstract

The effect of debinding temperatures on mechanical properties of sintered Fe-4%Ni alloy compacts made by injection molding has been studied. Specimens were made of carboyl iron and carbonyl nickel powder having average diameters of 5 and 2 μm respectively. After specimens were debound in temperature range from 503K to 553K with a holding period of 7.2ks in the air, they were sintered at a constant temperature of 1523K with a holding period of 7.2ks in the reduced pressure of 1Pa. In the case of debinding in the air, there is the critical debinding temperature at which oxide particles begin to form. Above the critical debinding temperature, oxide particles precipitate along grain boundaries and within grains. As the debinding temperature becomes higher, they grow mainly along grain boundaries. The mechanical properties of sintered compacts change drastically above the critical debinding temperature. The tensile strength of the compacts debound above the critical temperature, for instance, takes maximum value and its elongation is drastically lowered.