The potential of mechanical alloying to improve the strength and ductility of Mo–9Si–8B–1Zr alloys – experiments and simulation

Multi-phase Mo–Si–B alloys were intensively researched during the last decade as they are promising candidates for high temperature applications beyond the capabilities of single-crystalline Ni-based superalloys. Small additions of Zr improve the mechanical properties of the Mo solid solution phase (Moss), especially it lowers the brittle-to-ductile transition temperature and improves the fracture toughness. This work shows how mechanical alloying (MA) as the crucial step of powder metallurgical (PM) production will significantly influence the materials mechanical properties of Mo–9Si–8B–1Zr alloys in a wide temperature range from room temperature up to 1400 °C. The formation, continuity and length scale of the individual phases during PM processing is evaluated in detail using experimental methods and numerical studies. Furthermore, the mechanisms of deformation and fracture of the bulk materials are discussed with respect to the microstructural features. For comparison of the mechanical properties achieved by PM processing we produced the similar alloy composition by a conventional solidification process and characterized it by the same evaluation methods. [Display omitted] •MA affects homogeneity, morphology, and grain size of Mo–9Si–8B–1Zr powders.•Continuity and size scale of the constituents correlate to energy transfer by MA.•Optimized process leads to a continuous Moss phase and improved fracture toughness.•ZrO2 particles improve the mechanical strength of multi-phase Mo–9Si–8B–1Zr.•BDTT is reduced due to a continuous Moss phase as well as the Zr effect.