Abstract
Based on the continuous phase field model, the precipitation behavior of Cu rich phase in Fe-Cu-Mn alloy under the action of internal magnetic energy is studied. The effects of internal magnetic energy on the average particle radius, volume fraction and Gibbs free energy of Cu rich phase at different temperatures and different Mn content and Cu content are investigated. The simulation results show that the lower the Mn content and the higher the Curie temperature, the greater the contribution of internal magnetic energy to free energy is, and the contribution of internal magnetic energy decreases with temperature increasing. The internal magnetic energy reduces the phase structure transition barrier and promotes the phase structure transition. The volume fraction of precipitated phase increases with Cu content increasing. Compared with the effect of internal magnetic energy on the volume fraction of precipitated phase, the effect of internal magnetic energy leads to a large volume fraction of precipitated phase. Therefore, under the action of internal magnetic energy, the Cu rich phase has larger average particle size, volume fraction and smaller coercivity. Finally, the change trend of alloy hardness is predicted.
Highlights
the precipitation behavior of Cu rich phase in Fe-Cu-Mn alloy under the action of internal magnetic energy is studied
The simulation results show that the lower the Mn content
the contribution of internal magnetic energy decreases with the increase of temperature
Summary
IME 不仅影响相结构转变的 GFE,还对沉淀相长大阶段形貌有影响。图 2ae,f-j,k 分别为无 IME、有 IME 作用下的沉淀演化过程以及晶粒尺寸对应不同时 间步数的曲线。时效初期(t∗ < 7500),Cu 原子随机分布在 Fe 基体中,随着演化 的进行,溶质的过饱和为成核和结晶提供了化学驱动力,Cu 原子聚集形核,并 以吸收基体中 Cu 原子的方式不断析出。富 Cu 相不断长大并达到稳定的晶粒尺 寸。如图 2 所示,相同时间步数下,无 IME 作用下的成分起伏点更多,并且优 先析出沉淀相(如图 2-b 红色标注)。当析出相长大到一定尺寸时,有 IME 作用 下才出现个别沉淀相(如图 2-c、h 黄色标注)。当无 IME 作用下的沉淀相数量和 尺寸趋于稳定时,有 IME 下的沉淀相还处于长大阶段。对比可以发现 IME 对沉 淀相的形核演化过程有一定的阻碍作用。图 2-k 为演化过程中的颗粒半径变化图, 其中 No-IME 表示没有 IME 作用,With-INE 表示有 IME 作用,斜率的大小代表 了尺寸变化率的大小。对比两个状态下的平均颗粒半径,IME 作用下的平均半径 大于无磁能作用下的平均颗粒尺寸。并且在长大阶段,No-IME 状态下尺寸变化 率更高。当沉淀相的平均半径达到 2.69nm 时,尺寸变化率又趋于平缓,有 IME 作用下的平均颗粒半径以稳定的变化率呈线性增长,达到稳定时尺寸将不再变化。 说明 IME 对颗粒的长大过程和颗粒尺寸也有较大的影响,并且在 IME 的影响下 颗粒长大过程更加平稳。
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