Multicomponent Ni-rich high-entropy alloy toughened with irregular-shaped precipitates and serrated grain boundaries

A novel precipitation-strengthened multicomponent Ni-rich Ni46.23CO23Cr10Fe5Al8.5Ti4W2Mo1C0.15B0.1Zr0.02 (at.%) high-entropy alloy (HEA) was designed with strain-hardening after yielding rather than strainsoftening even at the temperature of 1000 degrees C. Due to the rapid onset of intergranular cracking, the HEA with spherical precipitates and straight grain boundaries was brittle, exhibiting an inferior tensile strength of similar to 220 MPa, and an insufficient uniform elongation of only similar to 1.9%. The serrated-grain-boundary architecture effectively overcomes this intergranular cracking issue. The resultant HEA with irregularshaped precipitates and serrated grain boundaries showed a brittle-to-ductile transition, giving in a superior strength up to as high as similar to 260 MPa while maintaining a uniform elongation of similar to 6.5%. Such an improvement of the strength and ductility has been attributed to the enhanced resistance of the serrated grain boundaries to the intergranular crack nucleation and propagation. Our current results provide a new method for the innovative design of high-temperature structural materials with superior mechanical performances. (C) 2021 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Automated summary

A novel precipitation-strengthened multicomponent high-entropy alloy was designed with optimized grain boundaries, showing a transition from brittleness to ductility and significantly improving both strength and ductility of the material.