Abstract The creep behaviour of directionally solidified SAC305 (96.5Sn-3Ag-0.5Cu wt%) alloy has been investigated with integrated particle matrix composite (PMC) crystal plasticity modelling and quantitative experimental characterisation and test. In this manuscript, the mechanistic basis of creep rate dependence is shown to be influenced by plastic strain gradients, and the associated hardening due to geometrically necessary dislocation (GND) density. These gradients are created due to heterogenous deformation at the β−Sn phase and intermetallic compound (IMCs) boundaries. The size and distribution of IMCs is important, as finer and well dispersed IMCs leading to higher creep resistance and lower creep rates, and this agrees with experimental observations. This understanding has enabled the creation of a new microstructurally homogenized model which captures this mechanistic link between the GND hardening, the intermetallic size, and the corresponding creep rate. The homogenised model relates creep rates to the microstructure found within the solder alloy as they evolve in service, when ageing and coarsening kinetics are known.

中文翻译：

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金属间化合物尺寸和形貌对Sn-3Ag-0.5Cu焊料蠕变速率的影响

摘要 利用集成颗粒基复合材料 (PMC) 晶体塑性建模和定量实验表征和测试，研究了定向凝固 SAC305 (96.5Sn-3Ag-0.5Cu wt%) 合金的蠕变行为。在这份手稿中，蠕变速率依赖性的机械基础被证明受塑性应变梯度的影响，以及由于几何必要的位错 (GND) 密度引起的相关硬化。这些梯度是由于 β-Sn 相和金属间化合物 (IMC) 边界处的异质变形而产生的。IMC 的尺寸和分布很重要，因为更细且分散的 IMC 会导致更高的抗蠕变性和更低的蠕变速率，这与实验观察结果一致。这种理解促成了一种新的微观结构均质模型的创建，该模型捕捉了 GND 硬化、金属间化合物尺寸和相应蠕变速率之间的这种机械联系。当老化和粗化动力学已知时，均质模型将蠕变速率与焊料合金中发现的微观结构相关联，因为它们在使用中演变。