The true transverse rupture strength calculated based on ab-initio methods for brittle Ti(C,N)-based cermets

The transverse rupture strength (TRS) is a key mechanical property for brittle Ti(C,N)-based cermets. However, the complicated structure with the ceramics hard phase and the metal binder phase makes it challenging to ascertain the essential impact on the TRS. To fundamentally understand the fracture in this system, herein, we present a theoretical model to investigate the essential TRS including friction stress at the phase boundary and Peierls stress of dislocations based on the first-principles method, in which the strain-stress method and Peierls-Nabarro method are employed. The traditional application of this method is analyzing the contributions to the yield strength (YS) in the constitution equation. In this article, we present a transformation of the TRS calculation into YS calculation in terms of some basic mechanical theories, thereby extending the applicability of this method to the calculation of TRS. And, the numerical valuations with good linear fit between the experimental TRS and calculated TRS including intrinsic strength, Hall-Petch effect, as well as dislocation density hardening provide solid evidence for the accuracy of our deductions and theoretical model. Finally, it is evident that the brittle components in cermets are not typically the ceramic phase itself. Our methodology illuminates a novel yet effective approach for analyzing fracture in Ti(C,N)-based cermets, which may be extended to other brittle materials in future.