Stress/strain aging mechanisms in Al alloys from first principles

First-principles based calculations were carried out to explore the possible mechanisms of stress/strain aging in Al alloys. Potential effects of temperature and external stress/strain were evaluated on the solvus boundary of Al3Se in Al-Sc alloy, and the interface energy of Al/θ＂ in Al-Cu alloys. Results show that applying tensile strain/stress during conventional aging can significantly decrease the solubility entropy, by red-shifting the phonon DOS at high states. The resulted solvus boundary would shift up on the phase diagram, suggesting a reduced solubility limit and an increased maximum possible precipitation volume of AlaSc in Al-Sc alloy. Moreover, the applied strain/stress has different impacts on the formation energies of different orientated Al/θ＂ interfaces in Al-Cu alloys, which can be further exaggerated by the Poisson effect, and eventually affect the preferential precipitation orientation in Al-Cu alloy. Both mechanisms are expected to play important roles during stress/strain aging.

低磷高效水处理剂研究进展

以羟基乙叉二膦酸（HEDP）和氨基三甲叉膦酸（ATMP）为代表的有机多元膦酸是目前广泛使用的一类水处理剂，它们较好解决了冷却水系统产生碳酸钙垢的问题，对金属的水腐蚀也有一定的缓蚀能力，C-P键的存在使其化学性能稳定，不易水解，且具有明显溶限效应和良好的协同效应。