Cr析出物硬化机理的原子尺度模拟研究

Hardening Mechanism Induced by Cr Precipitates: an Atomic Study

铁素体钢在热老化及辐照下会析出富Cr的α’相,该相会阻碍位错运动,引起材料硬化和脆化。研究位错与Cr析出物的相互作用机理是研究铁素体钢辐照硬化的前提。利用分子动力学方法(MD)研究BCC-Fe体系中Cr析出物与刃型位错(ED)的相互作用机理,并考虑Cr析出物尺寸、析出物中Cr含量、切过位置等因素的影响,结果表明:位错以切过的方式通过Cr析出物;Cr析出物对位错运动的阻碍作用随着析出物尺寸增大而增大;Cr析出物中的Cr含量越高,对位错运动的阻碍作用越强;当位错沿析出物赤道面通过时,所需临界剪切应力(CRSS)值最大。

Thermal and irradiation would result in the formation of Cr enriched α' phase in ferritic steels. The Cr precipitates can impede the mobility of dislocation, causing material hardening and embrittlement. Knowing the interaction mechanism between dislocation and Cr precipitates can help understand the irradiation hardening of ferritic steels. Using molecular dynamics(MD), the interaction between Cr precipitates and edge dislocation(ED) in BCC-Fe system was studied; the effects of precipitate size, Cr content in precipitate and cutting position on the pinning strength of Cr precipitate were estimated. The results show that: dislocation shear the Cr precipitate leaving no defects; the pinning strength increases with the size of Cr precipitate; Cr precipitate with higher Cr content is a stronger obstacle for dislocation; it shows highest CRSS when dislocation cutting along the equator plane of Cr precipitate.