Fe-Cu系合金纳米富Cu相析出演化规律的多尺度耦合模拟与实验研究

以美国开发的含铜HSLA系列钢为标志，Cu在新一代钢铁材料中的研究与应用受到广泛关注。Cu加入钢中后，依靠Cu的时效析出作用，可在对基体塑韧性无明显损害的情况下获得高强度。前期研究表明，Cu析出相的形态、尺寸、分布及与基体的位向关系等与钢的化学成分密切相关，但目前其机制与规律尚不清楚，影响了含Cu钢的经济高效使用。本项目拟设计系列Fe-Cu-X (X=Ni、Mn、Al）合金，通过TEM与3DAP表征，结合第一性原理计算，研究时效过程中合金元素在bcc Cu/α-Fe界面的分布形态及对界面能的影响；借助扩散偶实验与分子动力学模拟探究合金元素作用下Cu的扩散行为，进而揭示合金元素对富Cu相析出行为的影响机理。基于以上研究，建立考虑界面能、扩散系数及位错作用的析出动力学模型，阐明与富Cu相形核长大关联的主导机制及其对析出相热稳定性的影响规律，这对含铜HSLA钢的开发与应用具有重要理论与实际意义。

ABSTRACT：The research and application of Cu in the new generation of steel materials have attracted widespread attention since the Cu-bearing series of HSLA hull steel developed in the United States. In the steel, high strength can be obtained relying on the aging strengthening of Cu precipitation without significant damage to the plastic toughness. It have been reported that the morphology, size and distribution of Cu precipitates are closely related to the chemical composition of steel, as well as the orientation relationship between the precipitates and matrix. However, the mechanism and regularity of the Cu precipitates are not clear, which affects the economical and efficient use of Cu-bearing steel. In this project, a series of Fe-Cu-X (X=Ni, Mn, Al）alloys will be designed, and TEM and 3DAP characterization and the first principles calculation will be used to characterize the distribution of interfacial alloy elements and their effects on the interfacial energy during the aging process. The diffusion mechanism of Cu in the presence of other alloy elements will be investigated by means of diffusion couple experiment and molecular dynamics simulation. Consequently the influence mechanism of alloying elements on the Cu precipitation is to be explored. On the basis of the above study, taking account the interfacial energy, diffusion coefficient and dislocation the precipitation dynamics model effect will be developed, and reveal the dominant mechanism and its effect on the thermal stability of Cu-rich precipitation, which is of great theoretical and practical significance for the development and application of copper-containing HSLA steel.