Abstract
Thermal expansion properties and mechanical properties of the sintered Fe-Ni-Co alloys (Kovar), produced by the metal injection molding process using mixed and pre-alloyed powders, were investigated.
The average thermal expansion coefficients of the Kovar between 323K and 673K were 4.82×10-6/K for the mixed powder compacts and 5.03×10-6/K for the pre-alloyed powder compacts in the condition of reducing carbon content, because the thermal expansion property of the sintered Kovar depends upon the carbon content. The thermal expansion coefficients of the mixed powder compacts also were influenced by nickel content changing from 27wt% to 31wt%, each of the coefficients was 4.1×10-6/K and 11.4×10-6/K, respectively.
Reduction of silica(SiO2) in iron for the mixed powder improved the mechanical properties of the sintered Kovar, resulting in a tensile strength of 460MPa and an elongation of 36.4%. These properties exceed those of the sintered Kovar using pre-alloyed powder.
