相场法研究Fe-Cu-Mn-Al合金富Cu相析出机制
- 郭震1
,
- 赵宇宏1
,
- 孙远洋2
,
- 赵宝军1
,
- 田晓林3
,
- 侯华4
- 1. 中北大学材料科学与工程学院
- 2. 山西省太原市中北大学
- 3. 中北大学
- 4. 中北大学材料学院
基金项目: 省部级-山西省科技重大专项(20181101014,20191102008,20191102007)
摘要: 基于Ginzburg-Landau理论采用连续相场法模拟了Fe-15%Cu-3%Mn-xAl(x=1%,3%,5% 质量分数)合金在873K等温时效时纳米富Cu析出相沉淀机制及Al含量对富Cu相析出的阻碍效应。通过计算成分场变量和结构序参数,研究了富Cu析出相的形貌、颗粒密度、平均颗粒半径、生长和粗化动力学。研究结果表明:在时效早期阶段,纳米富Cu相通过失稳分解机制析出,由于原子扩散速率存在差异,从而形成以富Cu相为核心的核壳结构。随着时效时间延长,富Cu相析出物结构由BCC转变为FCC。其中Al和Mn原子在富Cu核外偏析形成Al/Mn簇,可以将其视为阻碍富Cu析出相形成的缓冲层;在沉淀过程中,随着Al含量的增加,Al/Mn金属间相促进了缓冲层的生长,阻碍富Cu析出相的生长和粗化。
Phase field study of the effect of Al on Cu-rich precipitates in Fe-Cu-Mn-Al alloys
- Received Date:
04 November 2020
Abstract: Low carbon steel plays an important role in many applications due to its high strength. Its high strength comes from the strengthening effect of nano-Cu-rich phase precipitates. In order to effectively adjust the microstructure of Cu-rich phase precipitates and obtain the best properties of Fe-Cu-based steel by adding different alloying elements (Mn, Al), it is necessary to understand the precipitation process of Cu particles. In this paper, based on the Ginzburg-Landau theory, the previous phase field model was modified, and the continuous phase field method was used to simulate the nanometer Cu rich precipitation process and Al content effect of Fe-15%Cu-3% Mn- x AL (x=1%, 3%, 5% mass fraction) alloy at 873K isothermal aging. The morphology, particle density, average particle radius, growth and coarsening kinetics of Cu rich precipitates phase were studied by calculating the component field variables and structural order parameters. The free energy was derived from CALPHAD and the microstructure evolution corresponds to the real alloy system. The results showed that in the early stage of aging, the nano-Cu-rich phase precipitates through a destabilizing decomposition mechanism. Due to the difference in atomic diffusion rate, a core-shell structure with Cu-rich phase as the core is formed. With the extension of aging time, the structure of Cu-rich phase precipitates changed from BCC to FCC. Among them, Al and Mn atoms segregate outside the Cu-rich phase precipitates to form Al/Mn clusters, which can be regarded as a buffer layer that hinders the formation of Cu-rich precipitates; during the precipitation process, as the Al concentration increases, the Al/Mn intermetallic phase of growth of the buffer layer and hinder the growth and coarsening of the Cu-rich precipitate phase.