根据实验测量的位向关系, 利用原子尺度计算研究了双相不锈钢中杆状奥氏体沉淀相的平衡截面形貌. 计算结果显示: 沉淀相的平衡形貌含有2个主要择优刻面, 且面积近似相等. 因此, 沉淀相计算截面形貌近似为菱形, 与实验观察形貌基本吻合. 通过对计算结果的分析, 给出了主要择优刻面上的具体位错结构, 也与实验测量结果基本吻合.

Assorted morphologies of precipitates in fcc/bcc transformation systems have been reported, which often exhibit irrational characteristic. Various models have been developed to explain the habit plane (or the broad facet), but the overall morphologies of the precipitates are seldom explained quantitatively. In this work, the equilibrium cross-section of rod-shape austenite precipitates in duplex stainless steel is determined by atomistic simulation. The input orientation relationship (OR) between fcc and bcc phase is determined according to the O-line criterion (one of the interfaces contains a single set of dislocations), with the condition that the invariant line lies in close-packed plane pair of and the Burgers vector of O-lines is . The obtained OR is close to the K-S OR , , with the deviation of 1.27° from the parallelism in both planes and directions. Interfacial energy of interfaces in various orientations in the zone axis of the invariant line has been calculated. To ensure the reliability of the calculated values, an initial atomic configuration free of interstitial and vacancy is constructed for each interface. The energies of the O-line interface, the interface normal to either or Δg₍₀₂₀₎ are found to have similar values, each at a local minimum. Based on the calculated interfacial energies, the equilibrium cross-section morphology is determined by the Wulff construction. The result shows that the morphology exhibits a near rhombus cross-section, which agrees consistently with experiments. One of the major facets is the O-line interface, normal to , in agreement with the observation. The other facet is normal to Δg₍₀₂₀₎ in the calculated result, while it is normal to in experimental results, with about 10^o difference between them. The discrepancy between calculated and observed results is probably because the experiments have not reached the equilibrium state. The dislocation structures in these three interfaces are identified from the atomic simulation results by a newly developed method based on the singular value decomposition of the Nye tensor. It confirms that the O-line interface contains a single set of [011]_f/2 dislocations with spacing of 1.5 nm. The interface normal to either or Δg₍₀₂₀₎ contains two sets of dislocations. The dislocation structure in the facet normal to is in good agreement with experimental observation of the non-O-line facet, including the local decomposition of dislocation core to stacking faults.