Order strengthening in α-CuAl alloys as influenced by grain size and solute content

✍ Scribed by Ari Varschavsky; Eduardo Donoso

• Publisher: Elsevier Science
• Year: 1988
• Tongue: English
• Weight: 778 KB
• Volume: 101
• Category: Article
• ISSN: 0921-5093
• DOI: 10.1016/0921-5093(88)90070-6

✦ Synopsis

7he yield stress dependence on grain size and solute content in preannealed and also in quenched polycrystalline a-Cu-Al alloys was measured. It was found that the Hall-Petch relation is valid for all the alloys in the two conditions. Preannealed materials, which are characterized by the presence of ordered domains, exhibit higher yieM stresses as a function of the inverse square root of the grain size arising from larger values of both the intercept o o and the Hall-Petch slope k v. As the alloys become more concentrated, the differences A ky and A oo between the preannealed and the quenched specimens increase for the same aluminium content. These results are interpreted in terms of the yield stress contribution of the ordered particles, in conjunction with the influence of the amount of solute segregation to grain boundaries on the slope value. It is" concluded that Akr> 0 is not the reflection of an interactive effect between grains and domains but is rather a consequence of the allowance of a higher grain boundary solute concentration in the ordered condition. Owing to the large domain volume fractions of the alloys having larger alurninium contents, the actual contribution to the yieM stress of disperse order was evaluated taking into account matrix depletion efJ'ects. In order to accomplish this, domain sizes and volume fractions were determined through microcalorimetric dissolution kinetics studies using current theories on sohae hardening. It was also estimated that the contribution of quenched-in vacancies to the yield stress was negligible at room temperature in all cases.