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论文类型：期刊论文

发表时间：2018-12-01

发表刊物：ENTROPY

收录刊物：SCIE、Scopus

卷号：20

期号：12

ISSN号：1099-4300

关键字：high entropy alloy; tensile creep behavior; microstructural evolution; creep mechanism

摘要：The tensile creep behavior of an equiatomic CoCrFeNiMn high-entropy alloy was systematically investigated over an intermediate temperature range (500-600 degrees C) and applied stress (140-400 MPa). The alloy exhibited a stress-dependent transition from a low-stress region (LSR-region I) to a high-stress region (HSR-region II). The LSR was characterized by a stress exponent of 5 to 6 and an average activation energy of 268 kJ mol(-1), whereas the HSR showed much higher corresponding values of 8.9-14 and 380 kJ mol(-1). Microstructural examinations on the deformed samples revealed remarkable dynamic recrystallization at higher stress levels. Dislocation jogging and tangling configurations were frequently observed in LSR and HSR at 550 and 600 degrees C, respectively. Moreover, dynamic precipitates identified as M23C6 or a Cr-rich sigma phase were formed along grain boundaries in HSR. The diffusion-compensated strain rate versus modulus-compensated stress data analysis implied that the creep deformation in both stress regions was dominated by stress-assisted dislocation climb controlled by lattice diffusion. Nevertheless, the abnormally high stress exponents in HSR were ascribed to the coordinative contributions of dynamic recrystallization and dynamic precipitation. Simultaneously, the barriers imposed by these precipitates and severe initial deformation were referred to so as to increase the activation energy for creep deformation.