Superplasticity of a multiphase refractory Mo–Si–B alloy

Mechanically alloyed Mo–Si–B alloys with a continuous α-Mo matrix and improved mechanical properties

“…The microstructure is still very fine after consolidation and as shown in Ref. [45] the material can be deformed superplastically at temperatures as low as 1300 C. This opens up the possibility of isothermal forging in closed dies to manufacture parts with intricate shapes and to subsequently coarsen the microstructure by heat treatment in order to improve the creep strength.…”

On the fracture toughness of fine-grained Mo-3Si-1B (wt.%) alloys at ambient to elevated (1300 °C) temperatures

“…At 1300 C, the strength of the Middlemas alloy is w30% greater than that of the ULTMAT alloy, while its ductility is only half as much. This effect is likely the result of the smaller grain size of the ULTMAT alloy, which allows for superplastic deformation at the reported strain rate [24,57]. The paucity of reported mechanical properties for Mo-Si-B makes a precise comparison difficult.…”

“…In fact, Jéhanno, et al showed that Mo-2.7Nb-8.9Si-7.7B (at.%) alloys can exhibit superplastic behavior at 1300 C at strain rates as high as 10 À3 s À1 [24,57]. Alloys tested under these conditions exhibited strains to failure in excess of 400% [24,57]. As the alloys can now be considered as ductile, intrinsic toughening associated with plasticity provides the dominant contribution to [21].…”

Viscosity control of borosilica by Fe doping in Mo–Si–B environmentally resistant alloys

“…The Mo-rich Mo-Si-B alloys are attractive for high-temperature structural applications due to high strength levels well above that for pure Mo, while offering some oxidation protection by the formation of a protective borosilica glass layer [1][2][3][4][5][6][7]. The alloys derive their ductility and fracture toughness from the presence of a continuous Mo(ss) matrix, which in cast alloys may require a Mo(ss) volume fraction greater than 40% [8,9].…”