Abstract
The CrCoNiSi_xAl_x(x = 0.1, 0.2) medium entropy alloys (MEAs) were designed to achieve significant improvement in strength and strain hardening via the minor addition of Si and Al elements to the CrCoNi MEA. The B2 + σ precipitation structure was formed on the CrCoNiSi_(0.2)Al_(0.2) MEA. Compared to CrCoNi MEA, the yield and ultimate tensile strengths of the CrCoNiSi_(0.2)Al_(0.2) MEA enhanced from 380 MPa to 850 MPa and 790-1287 MPa, respectively, while the uniform elongation was 23±5% that outperformed various advanced steels and Al-added MEAs/HEAs. The Orowan+shearing precipitation hardening mechanisms together with the deformation twins in a face-centered cubic (FCC) matrix were identified to improve the strength and strain hardening capacity. These findings provide guidance for the development of precipitation-hardened MEAs/HEAs with strength-ductility synergy.
NSTL
Elsevier