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摘要镍基合金是一类具有优异综合性能的合金。镍基合金的主要强化相为 γ′（Ni3Al）析出相，其在基体内含量，分布，大小等因素都将影响合金的性能。因而，对 γ′相时效过程的演化研究有重要意义。 本文采用相场法及热力学，通过 Matlab2012 编译程序，研究了时效温度与颗粒间距对Ni-Al 合金γ′相颗粒粗化过程的影响规律。 结果表明，随温度升高，析出相颗粒合并倾向增大，当温度 T 超过 1150K 时，两个颗粒发生了合并。通过研究不同温度下，体系内部的浓度分布，我们发现两颗粒间区域内的Al 原子其扩散方向为从体系外侧向颗粒间内侧扩散。温度的变化会影响颗粒间区域的平衡浓度，不合并的情况下，两颗粒间区域的浓度将为基体相平衡浓度；在合并的情况，两颗粒间区域的浓度为沉淀相浓度，为 cAl=0.25。颗粒间距的增大会使颗粒的合并倾向减弱，实验条件下，当间距 d超过6.3时，两个颗粒不能合并，在间距为 6 时，两颗粒合并。 50085
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毕业论文关键词 Ni-Al 合金 γ′沉淀相 合并 时效温度 颗粒间距
Title Three-dimensional Simulations of Merging Mechanism of γ′ Particles in Ni-Al Alloys
Abstract Ni-based alloy is a kind of alloy with high comprehensive performance，whose main strengthening phase is the γ′（Ni3Al）precipitation phase. The content and distribution in the matrix and size of γ′ precipitation phase would affect the performance of the alloy. Therefore, the research of the evolution of the aging process of γ′ phase has important significance. In this paper, the phase field method and thermodynamics theories were applied to the research. By using Matlab2012, procedures is compiled to study how the aging temperature and particle spacing affect γ′ phase particle coarsening process. Results show that with the temperature rise, merging tendency increases. When the temperature exceeds 1150 K, the two particles would merge. By studying the concentration distribution within the system, we found that the diffusion direction of Al atoms between the two particles is from the outside of the system to medial between particles. Temperature changes would affect the equilibrium concentration between the two particles. If the two particles merge, the concentration of the area between the two particles will be the equilibrium concentration of basic phase, else it will be 0.25.With the increase of particle spacing, the tendency of merging is weakened. Under the experimental condition, when the spacing of the two particles is more than 6.3, the two particles cannot merge. But in the span of 6, two particles can merge.
Keywords Ni-Al alloy γ′ precipitates Merge Aging temperature Particle spacing
目次
1绪论..1
1.1课题背景及研究意义1
1.2研究手段.2
1.3Ni基合金强化机理.3
1.4沉淀相粗化..4
1.5镍铝二元体系模拟研究进展5
1.6论文研究流程步骤..6
1.7课题具体研究内容..6
2理论模型及实验方案.7
2.1Ni-Al合金相场模型7
2.2Ni-Al合金物性参数及实验方案..9
3镍铝合金沉淀相微观形貌演化过程的研究..10
3.1不同时效温度下两颗粒的演化情况..10
3.2不同颗粒间距下双颗粒的演化情况..13
3.3本章小结16
4镍铝合金沉淀相演化过程中浓度分布的研究17
4.1不同条件下双颗粒径向浓度分布变化17
4.2不同条件下双颗粒对称面浓度分布变化.20
4.3时效温度对颗粒中心点浓度的影响..24