Yamakov V, Saether E, Phillips D R, Glaessgen E H
National Institute of Aerospace, Hampton, Virginia 23666, USA.
Phys Rev Lett. 2005 Jul 1;95(1):015502. doi: 10.1103/PhysRevLett.95.015502. Epub 2005 Jun 30.
A molecular-dynamics model for crack propagation under steady-state conditions is used to study dynamic instabilities along a grain boundary in aluminum that occur when the crack speed approaches 1/3 of the material's Rayleigh wave speed. Instead of crack branching, as is characteristic for a crack propagating in a homogeneous environment, the instability of an intergranular crack results in a periodic series of dislocation bursts. These bursts limit the crack speed and produce velocity oscillations with a large increase in energy dissipation that increases the grain boundary toughness.
一个用于研究稳态条件下裂纹扩展的分子动力学模型，被用来研究铝中沿晶界发生的动态不稳定性，这种不稳定性在裂纹速度接近材料瑞利波速度的1/3时出现。与在均匀介质中传播的裂纹所特有的裂纹分支不同，沿晶裂纹的不稳定性会导致一系列周期性的位错爆发。这些爆发限制了裂纹速度，并产生速度振荡，同时能量耗散大幅增加，从而提高了晶界韧性。
