The effects of dendritic arm spacing (as-cast) and aging time (solution heat-treated) of Al-Cu alloy on hardness

JOURNAL OF ALLOYS AND COMPOUNDS

卷:549

Article

Reis, B. P.¹  Franca, R. P.¹  Spim, J. A.²  Garcia, A.³  da Costa, E. M.¹  Santos, C. A.¹ 

[1] Pontifical Catholic Univ Rio Grande Sul PUCRS, Fac Engn, Porto Alegre, RS, Brazil

[2] Fed Univ Rio Grande Sul UFRGS, Dept Met, Foundry Lab, Porto Alegre, RS, Brazil

[3] Univ Campinas UNICAMP, Dept Mat Engn, Campinas, SP, Brazil

关键词: Al-Cu alloy;    Solidification;    Secondary dendrite arm spacing;    Solution heat treatment;    Natural aging;   

DOI  :  10.1016/j.jallcom.2012.09.041

来源: Elsevier

【 摘 要 】

The influences of dendritic arm spacing (as-cast condition) and aging times (solution treated condition) of a hypoeutectic Al-Cu alloy on hardness are analyzed in the present study. The solidification experiments were carried out at different conditions with respect to the cooling rate during solidification: cooled molds, and uncooled chill and sand molds. In any case, mold and metal were instrumented by thermocouples. Samples were extracted from all the castings and analyzed by optical microscopy in order to have the secondary dendrite arm spacing measured. These results were correlated with the solidification cooling rate and hardness. The samples were further subjected to solution heat treatment at a temperature of 540 degrees C for different solution times (8, 12, 16 and 28 h), followed by quenching in water at 25 degrees C. A solution time of about 12 h was shown to be the best condition for the solution heat treatment. After the solution heat treatment and during natural aging, the samples were analyzed by metallography and had their hardnesses measured. Experimental laws are proposed relating the resulting hardness to the aging time. (c) 2012 Elsevier B.V. All rights reserved.

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