A framework for plasticity in metallic glasses
Sungwoo Sohn, Naijia Liu, Geun Hee Yoo, Aya Ochiai, Jade Chen, Callie Levitt, Guannan Liu, Samuel Charles Schroers, Ethen Lund, Eun Soo Park, Jan Schroers
Abstract
The understanding and quantification of plasticity in crystalline metals, which has led to their widespread and effective usage as a structural material, is lacking in metallic glasses (MGs). Here, we introduce such a framework for plasticity. This very practical framework is based on a MGs’ ability to support stable shear band growth, quantified in a stress gradient, ∇σUS, which we measure and calculate for a range of MGs. Whether a MG deforms plastically prior to fracture or only elastic in an application is determined by the comparison between ∇σUS and the applied stress field gradient, ∇σapp; if ∇σUS>∇σapp, the MG can only deform elastic prior to fracture, if ∇σUS<∇σapp, the MG can plastically deform, and ∇σapp−∇σUS indicates the magnitude of plasticity. This framework can explain observed plastic properties of MGs and their apparent contradicting brittle and tough characteristics. Looking forward, proposed framework provides first MG specific constitutive relation to quantitatively model their plastic behavior in any application.