Effect of Debinding Conditions on Mechanical Properties of Sintered Fe-Ni Alloy Compacts Made by Injection Molding

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 carbonyl iron and carbonyl nickel powder having average diameters of 5 and 2 mu m respectively. After specimens were debound in the temperature range 503-553K with a holding period of 7.2 ks in air, they were sintered at a constant temperature of 1523K with a holding period of 7.2 ks in reduced pressure of 1 Pa. In the case of debinding in air, there is a 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 the maximum value and its elongation is drastically lowered.