TOPIC：

Metastable high-entropy alloys: design, structure and properties

REPORTER：

Zhiming Li, Max-Planck-Institut für Eisenforschung, Germany

TIME：

2018-05-23, 10:00am

SITE：

SJTU，徐祖耀楼room500

CONTACT：

付立铭

ABSTRACT：

Title：Metastable high-entropy alloys: design, structure and properties

Zhiming Li，Max-Planck-Institut für Eisenforschung, Germany，Email：zhiming.li@mpie.de

The concept of high-entropy alloys (HEAs) has drawn great attention as it opens a new realm of compositional opportunities for designing novel materials with exceptional mechanical, physical and chemical properties. HEAs were originally proposed to contain multiple principal elements in near-equimolar ratios to stabilize single-phase solid solutions through maximizing configurational entropy. By overturning this original concept which targets for the formation of single-phase solid solution, we recently developed a novel class of HEAs with multiple compositionally equivalent high-entropy phases and transformation-induced plasticity. In this talk, I will first introduce this type of metastable HEAs by shedding light on the corresponding design principles and highlighting their superior strength-ductility combinations compared to the corresponding single-phase HEAs. Then I will present our recent findings on designing interstitially alloyed metastable HEAs which shows the joint activation of twinning and transformation induced plasticity upon mechanical loading. Owing to the multiple deformation mechanisms active, the novel interstitial HEA shows further improved strength-ductility combination.

Key references:

[1] Z. Li*, et al., Metastable high-entropy dual-phase alloys overcome the strength-ductility trade-off，Nature, 534 (2016) 227-230.

[2] Z. Li*, et al., A TRIP-assisted dual-phase high-entropy alloy: grain size and phase fraction effects on deformation behavior，Acta Mater., 131 (2017) 323-335.

[3] Z. Li*, et al., Ab initio assisted design of quinary dual-phase high-entropy alloys with transformation-induced plasticity，Acta Mater., 136 (2017) 262-270.

[4] Z. Li*, et al., Interstitial atoms enable joint twinning and transformation induced plasticity in strong and ductile high-entropy alloys，Sci. Rep., 7 (2017) 40704.

[5] Z. Li*, et al., Strong and ductile non-equiatomic high-entropy alloys: design, processing, microstructure, and mechanical properties，JOM, 69 (2017) 2099-2106.