Excellent cryogenic temperature mechanical properties of L12 strengthened (CoCrNi)94Al3Ti3 complex concentrated alloy

Abstract

Metallic alloys with outstanding mechanical properties at cryogenic temperatures are in high demand for engineering applications such as cryogenic vessels. In this work, the mechanical properties of (CoCrNi)₉₄A₃Ti₃ at both room temperature (RT) and cryogenic temperature (77 K) were assessed. An increase in yield strength (Y.S) from 790 ± 25 MPa at RT to 1035 ± 10 MPa, at 77 K while ductility improvement from 45 % to 60 % was observed in the aged sample. Microstructural investigations revealed that the samples deformed at RT deformed predominantly via planar slip. The simultaneous increase in strength and ductility, higher strain-hardening behavior, and delayed necking of the alloy at 77 K are attributed to multiple deformation mechanisms, including dislocation slip, stacking faults, microbands, and twinning. The alloy exhibits one of the best combinations of strength and ductility at both RT and 77K, highlighting its potential for applications requiring superior mechanical performance in low-temperature environments.