Fabrication and mechanical characterization of Cu-Fe FGM produced by powder metallurgy method

Functionally graded materials (FGM) are a new type of composites with non-homogenous microstructure, which their physical and mechanical properties vary in the thickness direction continuously. Many researches in the field of property estimation, structural and thermal analysis of materials have been targeted. Different mechanical, physical and thermo-dynamical properties can be expected from these materials by changing the containing materials volume fraction. In this research, five layered Cu-Fe FGM specimens were fabricated with changing stepwise in the layers composition between pure copper and pure iron by powder metallurgy method. First the metal powders were compressed by press in high pressures and then the green specimens were sintered in a proper furnace was used to improve the layers connection and to increase the strength of the specimens. Two press systems containing uniaxial press and cold iso-static press were used in the fabrication of specimens to compare the results. Optical microscope was used to observe the microstructure and the combination of FGM layers. The results of microscopic investigations showed fine connectivity of the layers and powders and low density of pores in each layer. The produced Cu-Fe FGM specimens were tested in bending and tension to achieve their mechanical properties. The obtained stress-strain curves of these specimens showed enhancement in flexural and tensile strength of Cu-Fe FGM compared with the existing curves for pure copper and iron made by powder metallurgy method. Also cold iso-static press was highly more effective than uniaxial press in increasing the strength of specimens.