Preparation and compression behavior of Fe-Ni-P/porous-Fe/Fe-Ni-P composites

Porous-Fe-N alloys designed for light weight or energy absorption are inevitably facing the compromise of deteriorated mechanical properties. To optimize their mechanical properties, here a novel Fe-Ni-P/porous-Fe/Fe-Ni-P composite with sandwich structure was fabricated by spark plasma sintering and further strengthened via cryogenic treatment. Based on the principle of solid phase sintering and transient liquid phase sintering, porous core and dense outer layers formed simultaneously after co-sintering. The as-fabricated samples show excellent compressive strength of 1708 MPa, and after cryogenic treatment, due to the sufficient martensitic transformation, Fe-Ni-P outer layers show substantially increased hardness from 246.7 to 386.6 HV0.1 while the porous-Fe core remains unchanged. And the compressive strength maintains 1424 MPa despise the aggravated incongruity of deformation. The ratio of constituent microhardness R has been proposed to represent the hardness matching, and with decreasing R, the incongruity of deformation is intensified, and the nominal compressive strength is reduced.

Automated summary

A novel Fe-Ni-P/porous-Fe/Fe-Ni-P composite with sandwich structure was fabricated by spark plasma sintering and cryogenic treatment, showing excellent mechanical properties and hardness matching.