Microstructure evolution of fine-grain Fe–Cu composites during heat treatment in hydrogen

The microstructure evolution of Fe–30% Cu fine-grain composites during sintering of fine particle blends and during heat treatment of the high-density specimens up to 1130°C was investigated. The metal powder blends with particle sizes less than 0.1 μm were prepared by mechanical alloying technique. The quantitative analysis of microstructure was carried out. The microstructure of solid-state sintered composites was practically identical for all specimen treatment conditions and featured a high degree of dispersity and uniformity. Very fast coarsening of the microstructure took place at the temperature 1130°C during sintering powder blends and during heating of the high-density specimens. The mechanism of microstructure transformation is discussed. The solid-state treating Fe–30% Cu materials have high hardness and good conductivity after hardening. These characteristics impair immediately when the copper liquid-phase appears.