Fundamental Study of Brittle-to-Ductile Transition

9522661 Hsia这项理论与实验相结合的研究涉及解理断裂脆性到韧性转变（BDT）的建模。控制BDT的内在机制将通过检查裂纹尖端发生的两个相互竞争的过程来研究：解理裂纹扩展导致脆性断裂和位错产生，这是在韧性断裂过程中产生的固有塑性变形中发生的。本文将采用一种新的实验技术，即在温度梯度场中生长解理裂纹并测量由于位错产生而导致的裂纹止裂。对这一现象的基本理解至关重要的三个信息将被寻求：转变温度，发生转变时的裂纹速度，以及伴随转变的裂纹尖端的位错结构。＊＊＊

9522661 Hsia This combined theoretical/experimental study involves the modelling of brittle-to-ductile transition (BDT) in cleavage fracture. The intrinsic mechanisms controlling the BDT will be studied by examining two competing processes that occur at crack tips: cleavage crack propagation which results in brittle fracture and dislocation generation which occurs during the inherent plastic deformation that develops during ductile fracture. A novel experimental technique will be employed which involved growing a cleavage crack in a temperature gradient field and measuring the crack arrest due to dislocation generation. Three pieces of information essential to the fundamental understanding of this phenomena will be sought: the transition temperature, the crack velocity when the transition occurs, and the dislocation structure at the crack tip which accompanies the transition. ***