Consolidation of Fe-based metallic glassy powder by pressure infiltration and squeezing liquid phase sintering

In a previous paper we reported that slightly pressurized liquid phase sintering permits to fabricate fully dense Fe-based metallic glass composites, that the phase content of dual phase structure can be controlled by pressure squeezing of the liquid phase, and that the fracture strength increases with an increase in solid phase volume fraction. Throughout the process the pore shape at the contact of the particles, and accordingly the shape of the liquid phase at the particle contacts, were found to keep a cusp-shaped morphology, which implies and guarantees a complete penetration of the molten alloy into the pore space. In the present study, a model experiment was employed using a mono-sized spherical Fe-based metallic glassy powder to show an advantage of the present process for the fully dense composite structure and for the control of the composition of the two phase structure. Two types of experiments were conducted; one is pressure infiltration in which hot pressed solid skeleton was impregnated with a molten alloy, and the other is a squeezing liquid phase sintering, in which a mixture of the solid metallic glass powder and a liquid-phase alloy powder was hot pressed to control the relative density and the content of the liquid phase by squeezing out the molten alloy. The squeezing liquid phase sintering was found to give fully dense compacts, compared to the solid sintering of the metallic glass powder, which gives the relative density of 97.5% at most. An incomplete penetration of molten alloy into the dense preform and also the formation of peripheral pores near the die wall in the case of the infiltration process are discussed.