School of Materials Science and Engineering, China University of Mining and Technology, Xuzhou 221116, People's Republic of China.
Materials Science and Engineering, Johns Hopkins University, Baltimore, Maryland 21218, USA.
Phys Rev Lett. 2019 Jan 25;122(3):035501. doi: 10.1103/PhysRevLett.122.035501.
An empirical potential that has been widely used to perform molecular dynamics studies on the fracture behavior of FeP metallic glasses is shown to exhibit spinodal decomposition in the composition range commonly studied. The phosphorous segregation induces a transition from ductility to brittleness. During brittle fracture the atomically sharp crack tip propagates along a percolating path with higher P concentration. This embrittlement is observed to occur over a wide range of chemical compositions, and toughness decreases linearly with the degree of compositional segregation over the entire regime studied. Stable glass forming alloys that can be quenched at low quench rates do not, as a rule, exhibit such thermodynamically unstable behavior near to or above their glass transition temperatures. Hence, the microstructures exhibited in these simulations are unlikely to reflect the actual microstructures or fracture behaviors of the glassy alloys they seek to elucidate.
一种被广泛用于研究 FeP 金属玻璃断裂行为的分子动力学研究的经验势，在通常研究的成分范围内表现出旋节分解。磷的偏析导致延展性向脆性转变。在脆性断裂过程中，原子锋利的裂纹尖端沿着具有较高 P 浓度的渗透路径扩展。这种脆化现象在很宽的化学成分范围内都有观察到，并且韧性随着整个研究范围内组成偏析程度的线性降低而降低。能够以低淬火速率淬火的稳定玻璃形成合金通常不会在其玻璃转变温度附近或以上表现出这种热力学不稳定行为。因此，这些模拟中显示的微观结构不太可能反映它们试图阐明的玻璃态合金的实际微观结构或断裂行为。
