Unstable stacking fault energy and peierls stress for evaluating slip system competition in body-centered cubic metals

Determining the competition between the {110}(111), {112}(111) and {123}(111) slip systems in body-centered cubic (BCC) metals is important to understand their mechanical properties. In this paper, the unstable stacking fault energy (yus) and Peierls stress (up) of the three slip systems of a series of BCC metals are calculated in order to evaluate the competition among them. We find that yus of BCC metals is proportional to oB thorn G thorn =a2=3, where B, G and a are the bulk modulus, shear modulus and lattice constant, respectively. The calculations of yuss predict that the {110}(111) dislocation slip is prior to the {112}(111) and {123}(111) slips, however, yus may not be used to identify the priorities of the latter two slips because yuss of these two slip systems are too close to each other. According to ups, the mobility of dislocations decreases in the sequence of {110}(111), {112}(111), {123}(111) for all the metals considered except for K. Noticeably, it is shown that yus and up are not monotonically related to each other. (c) 2022 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).