Influence of pre-alloying on Fe-Cu based metal matrix composite

A pre-alloyed powder (i.e., Fe70Cu30), and elemental metal powders (i.e. Fe and Cu) were selected to study the mechanical properties and microstructures of two groups of Fe-Cu based metal matrix composite (MMC) samples. One group had different Fe/Cu ratios, and the other group had a fixed Fe/Cu ratio with different molten state contents (MSCs). Bending strength, Rockwell hardness and relative density of the samples were tested first, and then SEM and EDS were employed to analyze fracture surfaces of the samples after three-point bending test. Test and observation results show that both Fe/Cu ratio and MSC are significant to the mechanical properties and microstructure characteristics of the Fe-Cu based MMC samples. The mechanical properties increase with the decrease of Fe/Cu ratio at first, but sharply drop when Cu becomes the main ingredient, with the best performance of 1200 MPa and 98 HRB at Fe/Cu ratio of 7:3. The effects of Fe/Cu ratio also indicate that the strengths of bonding interfaces are different, and in descending order are Fe-Fe, Fe-Cu and Cu-Cu respectively. Simultaneously, mechanical properties increase with the rise of MSC in general with the optimal interval of Fe/Cu ratio for impregnated diamond bits being between 8:2 and 3:7. Micro fracture morphologies of the Fe-Cu based MMC samples also indicate that their fracture mechanism can be divided into brittle, plastic and transcrystalline fractures with MSC being the determinant. (C) 2021 Elsevier B.V. All rights reserved.