Atomic Simulation of the Interaction between Dislocation Line and Ferrite/Iron Oxide Interface
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摘要: 氧化铁是包含铁素体相的核级钢材（如低合金钢与铁素体-马氏体双相钢）在高温环境下常见的表面氧化物和内部析出物。正确认识氧化铁对钢材微观变形机制的影响对设计运行温度较高的先进核能系统的安全评估有重要意义。本文采用分子动力学方法研究了温度对铁素体中的刃型位错与铁素体/氧化铁两相界面的交互作用的影响。计算结果表明，在10~900 K的温度范围内，刃型位错均无法穿透铁素体/氧化物两相界面，而只引起两相之间发生一定程度的相互剪切变形。随着温度的上升，位错与界面接触点附近的应力集中程度随之升高，另外界面间剪切变形量也同时增高。以上结果对于高温环境下低合金钢和铁素体-马氏体双相钢的断裂失效分析有一定的指导意义。Abstract: Iron oxide is a common surface oxide and internal precipitate of nuclear grade steel containing ferrite phase (such as low alloy steel and ferrite-martensite dual phase steel) under high temperature. A correct understanding of the influence of iron oxide on the micro-deformation mechanism of steel is of great significance to the safety evaluation of advanced nuclear energy systems with higher operating temperatures. In view of this, the effect of temperature on the interaction between edge dislocations in ferrite and ferrite/iron oxide two-phase interface is studied by molecular dynamics method. The calculation results show that in the temperature range of 10~900 K, the edge dislocations can not penetrate the ferrite/oxide interface, but only cause a certain degree of shear deformation between the two phases. With the increase of temperature, the stress concentration near the dislocation-interface contact point increases, and the shear deformation between the interfaces also increases. The above results have certain guiding significance for fracture failure analysis of low alloy steel and ferrite-martensite dual phase steel under high temperature environment.
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图 1 包含刃位错的铁素体/氧化铁两相模型示意图
Figure 1. Schematic Diagram of Ferrite/Iron Oxide Two-phase Model Including Edge Dislocation
图 2 750 K温度下加载应变不同时由位错运动导致的原子剪切应变分布
Figure 2. Distribution of Atomic Shear Strain Caused by Dislocation Motion When Loading Strain Is Different at 750 K
图 3 加载应变达到0.05时不同温度情况下两相界面附近的原子剪切应变分布
T—温度
Figure 3. Distribution of Atomic Shear Strain Near Two-phase Interface at Different Temperatures When Loading Strain Reaches 0.05
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