Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
1575047 | Materials Science and Engineering: A | 2014 | 9 Pages |
Abstract
The precipitations in an Al-5.0Cu-0.3Mg (wt%) alloy and an Al-5.0Cu-0.3Mg-0.3Si (wt%) alloy have been systematically investigated by high-angle annular dark-field scanning transmission electron microscopy. The results are compared to clarify the effect of Si addition. The nucleation and growth process of θⲠ(Al2Cu) phase in Si-containing alloy during isothermal ageing at 180 °C is revealed in detail. The formation of Qâ³-type precipitates, on which the θⲠprecursors nucleate heterogeneously, contributes to the considerable increase in the ageing kinetics and higher strength at the early ageing stage. The thickening of the θⲠprecipitate is largely confined due to the rather small size of fine Qâ³-type precipitate. As a result, a large proportion of θⲠphase precipitates possess a specific thickness of 2cθⲠand change slightly during the entire observed duration of ageing. The θⲠgrowth mechanism distinct from the Al-Cu-Mg alloy finally leads to a refined θⲠmorphology regarding the thickness and aspect ratio (diameter/thickness). As is counterintuitive, the θⲠprecipitate thickness distribution is demonstrated to have little effect on the mechanical property steadiness at the late ageing stage of the Al-Cu-Mg-(Si) alloys.
Related Topics
Physical Sciences and Engineering
Materials Science
Materials Science (General)
Authors
L. Liu, J.H. Chen, S.B. Wang, C.H. Liu, S.S. Yang, C.L. Wu,