Low melting point metals such as Field’s metal and gallium are increasingly used as transition phases in stiffness-tuning soft materials and devices. Nevertheless, there is a knowledge gap on the fundamental constitutive behaviors of metals with melting points below 100℃. This letter reports the stress–strain relationships of Field’s metal at various temperatures and strain rates. This metal has the lowest melting point among metals and alloys whose constitutive behaviors have been studied systematically. Experimental results indicate that Field’s metal exhibits a strain-softening behavior, in oppose to the strain-hardening behaviors of most engineering metals and alloys. A modified Johnson–Cook model is devised in this letter to describe the constitutive behaviors of Field’s metal. The proposed model will facilitate the design and analysis of functional materials and structures consisting of Field’s metal.

低熔点金属（例如Field的金属和镓）越来越多地用作硬度调节软材料和设备的过渡阶段。然而，对于熔点低于100℃的金属的基本本构行为，仍然存在知识空白。这封信报道了在各种温度和应变速率下菲尔德金属的应力-应变关系。在已经系统地研究了本构行为的金属和合金中，这种金属的熔点最低。实验结果表明，与大多数工程金属和合金的应变硬化行为相反，Field的金属表现出应变软化行为。在这封信中设计了一种改良的Johnson-Cook模型，以描述菲尔德金属的本构行为。