论文标题
Cu-5wt％Ag中四面体沉淀和不连续沉淀的元素内成核
Intragranular nucleation of tetrahedral precipitates and discontinuous precipitation in Cu-5wt%Ag
论文作者
论文摘要
已知在CUAG合金中发生连续和不连续的降水。在30'期间在440 $^\ Circ $ c上老化的Cu-5％WTAG老化治疗Cu-5％WTAG后，通过原子探针断层扫描和透射电子显微镜进行了实验研究。已经观察到连续和不连续形成的沉淀物。位于谷物内部的沉淀物表现出两种不同的面形状：四面体和血小板形的沉淀物。还证明了在两个阶段之间接口处的高位不合适的位置也已证明。基于这些实验观察结果，我们检查了这些脱位对成核屏障的热力学效应，并表明奇特的形状是由于界面各向异性引起的。适当数量的不合适脱位会放松弹性应力，并导致能量有利的沉淀物。但是，由于母体和沉淀相之间的不合适，通常报告的CUAG合金的不连续降水可能是转化过饱和固体溶液的较低能量路径。我们建议，空位簇的存在可能有助于内部成核并减少
Both continuous and discontinuous precipitation is known to occur in CuAg alloys. The precipitation of Ag-rich phase has been experimentally investigated by atom probe tomography and transmission electron microscopy after ageing treatment of Cu-5%wtAg at 440$^\circ$C during 30'. Both continuously and discontinuously formed precipitates have been observed. The precipitates located inside the grains exhibit two different faceted shapes: tetrahedral and platelet-shaped precipitates. Dislocations accommodating the high misfit at the interface between the two phases have also been evidenced. Based on these experimental observations, we examine the thermodynamic effect of these dislocations on the nucleation barrier and show that the peculiar shapes are due to the interfacial anisotropy. The appropriate number of misfit dislocations relaxes the elastic stress and lead to energetically favorable precipitates. However, due to the large misfit between the parent and precipitate phases, discontinuous precipitation that is often reported for CuAg alloys can be a lower energetic path to transform the supersaturated solid solution. We suggest that the presence of vacancy clusters may assist intragranular nucleation and decrease
