Vacancy-tuned precipitation pathways in Al-1.7 Cu-0.025In-0.025Sb (at.%) alloy

被引：52
作者：
Zhang, Yong [1 ]
Zhang, Zezhong [1 ]
Medhekar, Nikhil V. [1 ]
Bourgeois, Laure [1 ,2 ]
机构：
[1] Monash Univ, Dept Mat Sci & Engn, Clayton, Vic 3800, Australia
[2] Monash Univ, Monash Ctr Electron Microscopy, Clayton, Vic 3800, Australia
来源：
ACTA MATERIALIA | 2017年 / 141卷
基金：
澳大利亚研究理事会;
关键词：
Aluminium alloys; Precipitation; Scanning transmission electron microscopy; DFT; Solute atoms; Vacancies; AL-CU ALLOYS; MG-SI ALLOYS; TRACE-ADDITIONS; ZONE FORMATION; SN ALLOY; ALUMINUM; NUCLEATION; THETA'; DIFFUSION; LIQUID;
D O I：
10.1016/j.actamat.2017.09.025
中图分类号：
T [工业技术];
学科分类号：
08 ;
摘要：
Microalloying is a routine method to optimize precipitation and mechanical properties in light metals. Here we study how In and Sb (0.025 at.%) additions in an Al-1.7 at.% Cu alloy benefit precipitation during ageing and investigate the underlying mechanism using scanning transmission electron microscopy and density functional theory (DFT) calculations. The combined additions accelerate precipitation kinetics and increase peak hardness through two different ways. In samples aged directly at low temperatures (<= 200 degrees C) after solid solution treatment, cubic close-packed InSb nanocrystals form first. The truncated {002} surfaces of InSb particles induce the preferential nucleation of Guinier-Preston (GP) zones, theta '' and theta' successively. However, in samples aged at 250 degrees C, precipitation of theta' precedes that of InSb particles. Supersaturated vacancies trapped by In and Sb solute atoms/clusters play a critical role in switching the precipitation sequence. By tuning how strong the binding between a vacancy and solute atoms is, we successfully invert the temperature dependence of the precipitation sequence. These findings will contribute to understanding precipitation mechanisms and optimizing precipitate distribution in aluminium precipitation hardenable alloys. (C) 2017 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.
引用
收藏
页码：341 / 351
页数：11
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