Center for Energetic Concepts Development, Department of Mechanical Engineering, University of Maryland, College Park, MD 21842, USA
Philos Trans A Math Phys Eng Sci. 2015 Mar 28;373(2038). doi: 10.1098/rsta.2014.0124.
A review is given of the analogous dependence on reciprocal square root of grain size or crack size of fracture strength measurements reported for steel and other potentially brittle materials. The two dependencies have much in common. For onset of cleavage in steel, attention is focused on relationship of the essentially athermal fracture stress compared with a quite different viscoplastic yield stress behaviour. Both grain-size-dependent stresses are accounted for in terms of dislocation pile-up mechanics. Lowering of the cleavage stress occurs in steel because of carbide cracking. For crack size dependence, there is complication of localized crack tip plasticity in fracture mechanics measurements. Crack-size-dependent conventional and indentation fracture mechanics measurements are described also for results obtained on the diverse materials: polymethylmethacrylate, silicon crystals, alumina polycrystals and WC-Co (cermet) composites.
本文综述了钢和其他潜在脆性材料的断裂强度测量结果，表明其与晶粒尺寸或裂纹尺寸的倒数平方根存在类似的依赖关系。这两种依赖性有很多共同之处。对于钢的解理起始，关注的重点是本质上无热的断裂应力与非常不同的粘塑性屈服应力行为之间的关系。这两种与晶粒尺寸有关的应力都可以用位错堆积力学来解释。由于碳化物体开裂，钢的解理应力降低。对于裂纹尺寸的依赖性，在断裂力学测量中存在局部裂纹尖端塑性的复杂性。还描述了对于不同材料（聚甲基丙烯酸甲酯、硅晶体、氧化铝多晶体和 WC-Co（金属陶瓷）复合材料）获得的结果，对常规和压痕断裂力学测量的裂纹尺寸依赖性进行了描述。
