Brittle fracture and the brittle-to-ductile transition of tungsten
Brittle fracture and the brittle-to-ductile transition of tungsten
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DOI：
10.1016/j.jnucmat.2003.08.009
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发表时间：
2003-12
影响因子：
3.1
通讯作者：
P. Gumbsch
中科院分区：
文献类型：
--
作者：
P. Gumbsch
本文的目的是简要回顾钨在脆性和半脆性区域断裂行为的实验观察和理论认识。通过微观模型和精心设计的实验的直接比较，在理解断裂过程的机理方面取得了进展。虽然需要原子模拟来分析脆性断裂模式，但位错模拟有助于分析在脆韧性转变(BDT)以下的半脆性区域内本征断裂韧性与预变形、温度或加载速率的关系。通过对钨单晶的断裂实验与模拟结果的比较，表明位错成核是低温下的限制因素，而中温时对加载速率的依赖要求位错的能动性起控制作用。此外，研究还表明，在BDT温度以下的中间温度区域只有一个唯一的激活能。最后，将计算结果与所选的多晶钨数据进行了比较。
The aim of this paper is to shortly review the experimental observations and the theoretical understanding of the fracture behaviour of tungsten in the brittle and semi-brittle regime. Advances in the understanding of the mechanisms of fracture processes are made by direct comparison of microscopic modelling and carefully designed experiments. While atomistic simulations are needed to analyse the brittle fracture regime, dislocation simulations are helpful in analysing the dependence of the intrinsic fracture toughness on pre-deformation, temperature or loading rate in the semi-brittle regime below the brittle-to-ductile transition (BDT). By such comparison of fracture experiments on tungsten single crystals with simulations it is shown that dislocation nucleation is the limiting factor at low temperatures, while the dependence on loading rate at intermediate temperatures requires that dislocation mobility takes control. Furthermore, it is shown that the intermediate temperature regime up to the BDT temperature scales with one unique activation energy. At last the results are compared to selected data on polycrystalline tungsten.