Effects of Mechanical Milling and Sintering Temperature on the Densification, Microstructure and Tensile Properties of the Fe–Mn–Si Powder Compacts

摘要

This work reported on the effects of mechanical milling and sintering temperature on the densification,microstructure and mechanical properties of the Fe–28Mn–3Si(wt%) alloy. Elemental Fe, Mn and Si powders were used as the starting materials, and two batches of powder mixture were prepared: one was blended elemental(BE) powder mixture; the other was mechanically milled(MM) powder mixture milled for5 h using planetary ball milling. Both powder mixtures were pressed under a uniaxial pressure of 400 MPa,and subsequently sintered in a high vacuum furnace for 3 h at 1000, 1100, 1200 and 1300 °C. It was found that Mn depletion region(MDR) was formed on the surface of all the sintered samples. The sintered BE compacts had a low density(<68.2%) at all temperatures, while the density of the sintered MM compacts increased drastically from ~65% at 1000 °C to ~91% at 1300 °C. All the sintered MM compacts were composed of a predominant γ-austenite and minor ε-martensite. In comparison, additional(Fe, Mn)3Si phase was observed in the BE alloys sintered at 1000 °C, and a single α-Fe phase was identified in the BE compact sintered at 1300 °C. The tensile properties of the sintered MM compacts increased significantly with the temperature and were significantly higher than those of their BE counterparts.