-
以相场方法模拟模型合金时效过程中沉淀颗粒的劈裂现象. 模拟计算表明, 模型合金溶质原子浓度为c=0.1溶质原子分数、初始晶核尺寸在80l到90l(l=12.18 Å)之间单一颗粒会发生劈裂, 颗粒劈裂是系统弹性能和系统界面能通过扩散交互作用的结果. 在时效初期, 初始球形颗粒在弹性能占绝对优势作用下, 界面沿方向尖锐化, 导致溶质浓度在沉淀的四角富集而在心部贫化, 为颗粒劈裂创造了成分条件, 此为颗粒劈裂的孕育期, 表现为系统总界面能在此期间为一水平台阶. 经过成分孕育的沉淀颗粒在300τ (τ=4.65 s)时开始劈裂, 时效1000τ劈裂结束时系统总界面能达到极大值点而总弹性能达到极小值点. 计算发现, 颗粒劈裂孕育期系统总界面能的水平台阶和劈裂结束时的能量极值点是颗粒劈裂为4块的典型特征. 初始晶核尺寸大于90l的颗粒时效期间只有界面能孕育期水平台阶而没有能量的极值点, 而初始晶核尺寸小于80l的颗粒界面能能单调递增.The splitting of particles precipitating from solid solutions, e.g. Ni-based alloy, is studied with the phase field method. The simulation results show that in the single particle system, the nucleuses of crystal with the sizes of 80l to 90l (l= 12.18 Å) split during ageing. The splitting is the result of the interaction between elastic energy and interface energy. During the earlier stage of ageing, the sharpening along of the interface of the initial spheric shape particle will lead to the solute beneficiation at the corner but impoverishment in the center of the particle, it is the splitting incubation stage (SIS). The total interface energy (TIE) appears as being of horizontal step during SIS. The particles split at 300τ (τ=4.65 s) after the SIS and at the end of splitting the TIEs reach their maxima and the total elasic energy (TEE) reaches minimum at 1000τ. The horizontal step during SIS and the extreme points of TIE and TEE are the representative features of splitting. The TIE has SIS but no extreme point lying on TIE and TEE when the particle sizes are bigger than 90l. For the particles with sizes smaller than 80l, the TIE increases up monotonically.
-
Keywords:
- splitting/
- interface energy/
- elastic energy/
- incubation stage
[1] [2] [3] [4] [5] [6] [7] [8] [9] [10] [11] [12] [13] [14] -
[1] [2] [3] [4] [5] [6] [7] [8] [9] [10] [11] [12] [13] [14]
计量
- 文章访问数:6005
- PDF下载量:300
- 被引次数:0
下载: