Alloying of MoSi2 for improved mechanical properties

Effects of alloying on mechanical properties of solidification processed polycrystalline MoSi2, ternary (Mo, 2.5 at.% Re)Si2, Mo(2 at.% Al, Si)2, (Mo, 1 at.% Nb)Si2, and quaternary (Mo, 1 at.% Re)( 2 at.% Al, Si)2 alloys were evaluated by microhardness testing at room temperature and compression testing at elevated temperatures. Alloying with 2.5 at.% Re resulted in an anomalously high solid solution hardening in MoSi2, while alloying with 2 at.% Al lowered the brittle-to-ductile transition temperature, in compression, of polycrystalline MoSi2 from 900 oC to ⩽25 oC. Similar to the effects observed in the quaternary (Mo, 1 at.% Re)(2 at.% Al, Si)2 alloy, 1 at.% Nb containing samples exhibited concurrent enhanced ambient temperature ductility and higher elevated temperature strength compared to pure MoSi2. The effects of alloying MoSi2 with 2.5 at.% Re, 1 at.% Re+2 at.% Al, and 1 at.% Nb on hardness and yield strength are discussed.