Abstract
The tensile creep behavior of Cr-Si alloys with Cr ≥ 91 at.% was investigated in air at 980 °C with a constant load of 50–100 MPa. Additionally, the influence of substitutional alloying additions of 2 at.% Ge and Mo, leading to ternary alloys was studied. The addition of Ge or Mo results in an improvement in creep strength, with the highest strength achieved with addition of Mo. For longer creep exposure times a strong effect is observed, because of severe nitrogen uptake from the air, depending on alloy composition. Based on the results a novel mechanism for the impact of chromium nitride formation on the creep behavior is proposed.
Highlights
New materials are required that can operate at higher temperatures to enable a further increase in efficiency of high temperature applications e.g., turbine engines
Refractory metals and refractory metal-based alloys offer the possibility for a further increase in working temperature due to their high melting points
The Cr-Si system offers the lowest density of about 6.5 g/cm3 [4], which is significantly lower than the 8–9 g/cm3 of commercially used superalloys
Summary
New materials are required that can operate at higher temperatures to enable a further increase in efficiency of high temperature applications e.g., turbine engines. Refractory metals and refractory metal-based alloys offer the possibility for a further increase in working temperature due to their high melting points. Among the known refractory alloys, silicide systems such as Mo-Si-B, Nb-Nb5 Si3 and Cr-Cr3 Si offer promising properties [1,2,3]. The Cr-Si system offers the lowest density of about 6.5 g/cm3 [4], which is significantly lower than the 8–9 g/cm of commercially used superalloys. A reduction in weight in addition to higher operating temperatures would increase the efficiency of turbine engines. Chromium shows low creep resistance at temperatures above
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