Mechanical properties and wear resistance of Fe–Ni–Cu-based metal matrix composites reinforced with hollow corundum microspheres

Abstract

This paper focuses on the development of composite materials based on the Fe–Ni–Cu alloy with hollow corundum microspheres (HCM). The composites were produced by means of powder metallurgy: by mixing initial metallic powders in various types of mixers followed by hot pressing. Compact samples of Fe–Ni–Cu + HCM composites featured high relative density and microstructure homogeneity. The introduction of HCM leads to a decrease in strength to 30 % (from 1125 MPa to 800 MPa at a HCM concentration of 15 vol.%). However, resulting composite materials retained high plasticity. It was established by the micromechanical modeling method that such composites have stress concentration regions not at the interface between HCM and the matrix, but on the inner surface of microspheres. On the contrary, the adjacent matrix volume around HCM features stress relaxation and «unloaded» regions formed. HCM introduction into the matrix based on the Fe–Ni–Cu alloy increases wear resulting from friction on M300 concrete by 50–170 % with a grain size of 70–100 μm and by 160–325 % with a grain size of 100–140 μm. During friction, HCMs act as a reservoir for debris (concrete particles), so the matrix surface remains free of wear products and directly contacts the material processed. The heavy wear of composites with HCM makes them promising for use as a binder in diamond tools designed for the dry cutting of concrete and reinforced concrete.