[SY-E2] Symposium E-2

[SY-E2] Intrinsic Ductility of Alloys from Nonlinear Elasticity

^○Ian Winter^1,2, Maarten de Jong^1,3, Daryl Chrzan^1,2 (1.University of California, Berkeley, United States of America, 2.Lawrence Berkeley National Laboratory, United States of America, 3.SpaceX, United States of America)

The direct computation of the ideal strength of an alloy is confounded by the lack of formal crystalline symmetry. A simple analytical method to estimate the ideal strength and to study intrinsic ductility of a crystalline solid using higher-order elastic constants is presented. Since the method is rooted in parameters that are easily calculated, even for disordered systems, it can be applied to study the properties of alloys. This method estimates the stress and strain associated with elastic instability and yields the detailed mode of the instability. It is noted that ductility and brittleness are relative. A parameter gauging the relative intrinsic ductility of a material is introduced, and is shown to be consistent with experimental measurements of elongation for a number of materials. Finally, the model is applied to the study of a chemically complex alloy, W-Nb-Mo-Ta-V, and is used to suggest shifts in composition that will increase the ductility of the alloy. The work is supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, Materials Sciences and Engineering Division under Contract No. DE-AC02-05-CH11231 (Materials Project program KC23MP).