Nanoindentation responses of NiCoFe medium-entropy alloys from cryogenic to elevated temperatures  

作　　者：Qin-qin Xu Kamran Karimi Amirhossein H.Naghdi Wen-yi Huo Chong Wei Stefanos Papanikolaou 

机构地区：[1]NOMATEN Centre of Excellence,National Centre for Nuclear Research,Otwock 05-400,Mazowsze,Poland [2]College of Mechanical and Electrical Engineering,Nanjing Forestry University,Nanjing 210037,Jiangsu,China [3]Science and Technology on Thermo Structural Composite Materials Laboratory,Northwestern Polytechnical University,Xi'an 710072,Shaanxi,China [4]School of Mechanics,Civil Engineering and Architecture,Northwestern Polytechnical University,Xi'an 710072,Shaanxi,China

出　　处：《Journal of Iron and Steel Research International》2024年第8期2068-2077,共10页钢铁研究学报（英文版）

摘　　要：NiCoFe alloy,a medium-entropy alloy,shows potential for applications in extreme environments.However,there is a theoretical barrier concerning the unclear understanding of its high-temperature dislocation motion mechanism.The load response exhibits distinct signatures relevant to thermal activation,most notably a decrease in critical force(i.e,softening)from cryogenic to elevated temperatures,e.g.,from 200 to 1000 K.The onset of plasticity is characterized by the nucleation of stacking faults and prismatic loops at low temperatures,whereas the surface nucleation of Shockley partial dislocations dominates plasticity at elevated temperatures.We show that thermal effects lead to non-uniform atom pile-ups and control the rate of phase transformation with increasing indentation depth.The findings in this work extend the understanding of the mechanical response of NiCoFe alloys under indentation at different temperatures,shedding light on the underlying dislocation motion mechanisms and surface deformation characteristics.The observed transformation-induced plasticity mechanism has implications for the properties of medium-entropy alloys and their potential applications in extreme environments.

关 键 词：ORIENTATION Dislocations Mechanical behaviors Phase transition 

分 类 号：TG13[一般工业技术—材料科学与工程]