| Abstract Scope |
Conventional processing routes for UHTCs are generally assumed to yield reproducible materials when raw materials and nominal parameters are constant. However, significant variability in density, microstructure, and mechanical properties is frequently observed, suggesting the presence of uncontrolled or unrecognized process variables.The role of such hidden variables is examined through representative examples. First, powder ultrasonication increased the strength by more than 100 MPa, due to reduced critical flaw size by improved powder deagglomeration and suppressed abnormal grain growth.Second, an exceptionally strong material was obtained via a standard processing route, but could not be reproduced until it was discovered that trace impurities were unintended introduced by “dirty” milling media.Stochastic and often overlooked factors can strongly influence process–structure–property relationships in UHTCs. Understanding and quantifying these sources of uncertainty is essential for developing robust processing protocols, models and enabling reliable performance in extreme environments. |