Characterization of Fe-Cu-Ni composites sintered by hot-press

The main objective of the work was to determine the effects of powder composition on a microstructure and properties of iron-base materials used as matrices in diamond impregnated tools. Mixed powders and 30 hours Fe-Cu-Ni milled powders were used for the experiments. The influence of manufacturing process parameters on microstructure and mechanical properties of sinters was investigated. Sintering was performed in a graphite mould using a hot-pressing technique. The powders were consolidated to a virtually pore-free condition during 3 min holding under 35 MPa and at 900°C. The investigations included: density, hardness, static tensile test and X-ray diffraction (XRD) analysis. Observations were also made of microstructure and fracture surfaces of broken samples using a scanning electron microscope (SEM) were also conducted. The SEM observations revealed an evident dependence of grain size and microstructural homogeneity on milling time. The obtained test results indicate that the sinters are virtually densified, have good plasticity with relatively high hardness and yield strength, but sinters of non-ground powders are characterized by a coarse-grained microstructure. (paper)