| Full text | |
| Author(s): |
Kakitani, Rafael
[1]
;
Reyes, Rodrigo V.
[2]
;
Garcia, Amauri
[1]
;
Cheung, Noe
[1]
;
Spinelli, Jose E.
[2]
Total Authors: 5
|
| Affiliation: | [1] Univ Estadual Campinas, UNICAMP, Dept Mfg & Mat Engn, BR-13083860 Campinas, SP - Brazil
[2] Univ Fed Sao Carlos, Dept Mat Engn, BR-13565905 Sao Carlos, SP - Brazil
Total Affiliations: 2
|
| Document type: | Journal article |
| Source: | METALLURGICAL AND MATERIALS TRANSACTIONS A-PHYSICAL METALLURGY AND MATERIALS SCIENCE; v. 50A, n. 3, p. 1308-1322, MAR 2019. |
| Web of Science Citations: | 1 |
| Abstract | |
Unsteady solidified microstructures of the Al-15 wtpct Si-1.5 wtpct Mg alloy under two degrees of melt superheating are examined: 4 and 21pct above the alloy liquidus temperature. The dendritic array and the eutectic mixture have been investigated, which are affected not only by the solidification kinetics but also by the melt superheating. The directional solidification experiments permitted that aligned Al-rich dendrites could be formed for both high- and low-melt superheatings. These dendrites appear as islands' isolated from each other and dispersed within the -Al+Si+Mg2Si eutectic matrix. Such configuration arises in samples under the entire range of examined cooling rates, i.e., from 0.5 to 50 K/s. Directionally solidified samples having different -Al dendrite interphase spacings have been characterized and subjected to tensile tests. Such microstructural spacings translate the effectiveness in blocking the dislocations motion during loading, which is promoted mainly by the dendritic/eutectic boundaries. This mechanism is especially operative since the applied tensile load is perpendicular to the dendritic growth path. As such, the evolution of tensile properties as a function of these spacings was assessed. Both elongation () and the ultimate strength (sigma(u)) are enhanced nearly by 40pct due to the reduction in the dendrite interphase spacing. The highest properties (sigma(u): 310MPa and : 7pct) are associated with a microstructure formed by aligned dendrites with 70m in spacing embedded in a eutectic mixture. Three factors appear to contribute to the higher strength values observed for the alloy processed under lower-melt superheating, i.e., higher fraction of dendrites, solid solution strengthening of Mg in -Al, and finer eutectic Si spacing. (AU) | |
| FAPESP's process: | 17/12741-6 - Application of experimental solidification techniques, characterization of microstructure and properties in the evaluation of eutectic and hypereutectic Al-base and Zn-base alloys |
| Grantee: | José Eduardo Spinelli |
| Support Opportunities: | Regular Research Grants |