一、问题的提出高强度金属构件的低应力脆性断裂,给传统的合金强化、选材及强度设计带来了无法克服的困难。材料断裂力学的出现及其进展,尤其是它提出的有关金属断裂强度的力学模型,为解决这些难题提供了理论依据。1.金属的理论强度——Frenkel 模型 First, the issue put forward High-strength low-stress brittle fracture of metal components, to the traditional alloy strengthening, material selection and strength design has brought insurmountable difficulties. The emergence of materials fracture mechanics and its progress, especially its proposed mechanical fracture strength of the metal model, to solve these problems provide a theoretical basis. 1. The theoretical strength of metal - Frenkel model