Thermal Stability of Near Nanostructured Bulk Cryomilled 5083Al Alloy NSF Grant: MET DMR-0304629

1. Upper Limit Fig. 3 Fig. 2 Thermal Stability of Near Nanostructured Bulk Cryomilled 5083Al Alloy NSF Grant: MET DMR-0304629 Farghalli A. Mohamed, Indranil Roy and Manish Chauhan University of California, Irvine Where Dois the initial grain size, Q is the activation energy for grain growth, ko is constant, and Dmis the maximum attainable grain size, at a particular temperature, Tm. Motivation:Bulk ultrafine grained (UFG) Al-Mg alloy prepared by cryomilling and consolidation with an average grain size of ~ 300 nm has the potential for use in engineering applications at high temperatures. Accordingly, the study of its thermal stability is a necessity. Upper limit of the usage of BULK UFG 5083 Al alloy Research Findings: Characteristics of Grain Growth It is evident from the Fig. 2 that the change in Dm with annealing temperature is rather small at lower temperatures, but increases considerably at temperatures above 550 K. On this basis it can be suggested that the upper limit of using this material in commercial applications is about 550 K. The plot of elongation to failure vs. annealing temperature (Fig. 3) also supports the result inferred from Fig. 2. It is clear from Fig. 3 that ductility reaches a maximum value at about 550. The research is significant in terms of defining the upper limit of using this material in commercial applications as about 550 K Fig.1: A plot of grain size (D) data vs. annealing time (t). At temperatures (T) higher than 623 K, significant grain growth occurs. For constant temperature, the grain growth decreases with increasing time. Examination of the microstructure shows the presence of nanoscale dispersion particles that impede boundary migration. Under this condition, Burke’s model as presented by the following equation is applicable.