Alloying of MoSi2 for improved mechanical properties

Effects of alloying on mechanical properties of solidification processed po lycrystalline MoSi2, ternary (Mo, 2.5 at.% Re)Si-2, Mo(2 at.% Al, Si)(2), ( Mo, 1 at.% Nb)Si-2, and quaternary (Mo, 1 at.% Re)(2 at.% Al, Si)(2) alloys were evaluated by microhardness testing at room temperature and compressio n testing at elevated temperatures. Alloying with 2.5 at.% Re resulted in a n anomalously high solid solution hardening in MoSi2, while alloying with 2 at.% Al lowered the brittle- to-ductile transition temperature, in compres sion, of polycrystalline MoSi2 from 900 degreesC to less than or equal to 2 5 degreesC. Similar to the effects observed in the quaternary (Mo, 1 at,% R e)(2 at.% Al, Si)(2) alloy, 1 at.% Nb containing samples exhibited concurre nt enhanced ambient temperature ductility and higher elevated temperature s trength 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 ar e discussed. (C) 2001 Elsevier Science Ltd. All rights reserved.