Zn对Al-Mg-Si合金时效析出相稳定性影响的第一性原理研究  

Effects of Zn on the Stability of the Aging Precipitates in Al-Mg-Si Alloys byFirst Principles Calculations

作　　者：余瑞 张永安 李亚楠[1,2,3] 李锡武 李志辉 闫丽珍[1,2,3] 温凯 熊柏青[1,3] YU Rui;ZHANG Yong’an;LI Yanan;LI Xiwu;LI Zhihui;YAN Lizhen;WEN Kai;XIONG Baiqing(State Key Laboratory of Non-ferrous Metals and Processes,GRINM Group Co.,Ltd.,Beijing 100088,China;GRIMAT Engineering Institute Co.,Ltd.,Beijing 101407,China;General Research Institute for Nonferrous Metals,Beijing 100088,China)

机构地区：[1]有研科技集团有限公司有色金属材料制备加工国家重点实验室,北京100088 [2]有研工程技术研究院有限公司,北京101407 [3]北京有色金属研究总院,北京100088

出　　处：《材料导报》2023年第4期154-158,共5页Materials Reports

基　　金：国家重点研发计划(2016YFB0300802)。

摘　　要：6000系Al-Mg-Si合金综合力学性能优良,具有比强度高、成型性能好、焊后表面质量高、耐腐蚀性好等特点,目前已经广泛应用于制造汽车车身板材。该系合金为可热处理强化合金,可以通过提高合金的时效响应速度,使合金在时效过程中获得尽可能大的强度提升。目前常用的措施是在合金中添加少量的Zn元素来促进时效析出,但Zn对合金时效析出相稳定性的影响却尚不明确。因此,本工作主要采用第一性原理计算的方法,计算了添加Zn的Al-Mg-Si合金中可能形成的Mg-Si相(包括Mg-Si GP区、β″相)和Mg-Zn相(包括Mg-Zn GP区、η′相)的晶格常数、形成焓。其中Mg_(2)Si_(1)Al_(3)、Mg_(2)Si_(3)Al_(6)、AlMg_(4)Si_(6)、Mg_(1)Si_(1)四种可能的Mg-Si GP区晶胞的形成焓从大到小为Mg_(2)Si_(1)Al_(3)、Mg_(2)Si_(3)Al_(6)、AlMg_(4)Si_(6)、Mg_(1)Si_(1),均低于Mg-Zn相的形成焓,说明Mg_(1)Si_(1)结构的GP区最稳定,且在添加少量Zn元素的Al-Mg-Si合金中很难形成Mg-Zn相。随后又进一步计算了Zn原子在Mg_(1)Si_(1)GP区和峰时效态析出相β″相中掺杂前后的晶格常数、形成焓、电子态密度,结果表明Zn原子的掺杂能够降低Mg-Si GP区和β″相的形成焓并提高其共价键强度,从而可能促进时效过程中Mg-Si GP区和β″相的形成,提高合金的时效响应速度。Al-Mg-Si alloys are widely used in automobiles due totheir sufficient strength,high surface quality after welding and excellent corrosion resistance.As a series of heat-treatable alloys,Al-Mg-Si alloys’strength can be improved as much as possible by increasing the aging response rate.At present,Zn is generally added to the alloys to promote the aging precipitation,but the effects of Zn on the stability of the aging precipitates are still unclear.Thus,the lattice constants and formation enthalpies of possible Mg-Si phases(including Mg-Si GP zones,β″phase)and Mg-Zn phases(including Mg-Zn GP zones,η′phase)in Al-Mg-Si alloys with Zn added were calculated using first-principles calculation.The results reveal that the formation enthalpies of the four possible structures of Mg-Si GP-zones are in the order of Mg_(2)Si_(1)Al_(3)>Mg_(2)Si_(3)Al_(6)>AlMg 4 Si 6>Mg_(1)Si_(1),which are all lower than that of Mg-Zn phases,indicating that the Mg_(1)Si_(1)structure is the most stable one,and it is difficult to form Mg-Zn phases in Al-Mg-Si alloys containing Zn element.Furthermore,the lattice constant,formation enthalpy,and electronic density of states of Zn atoms before and after doping in the Mg1Si1 GP region and the peak-aged precipitated phaseβ″phase were calculated.The results showed that the doping of Zn can reduce the formation enthalpies of Mg-Si GP-zones andβ″phase,and increase the width of pseudoband gap.The formation of GP-zones andβ″phase during the aging stage of Al-Mg-Si alloys is promoted due to the improved stability of the structures.As a result,the aging hardening response of the alloys is improved.

关 键 词：AL-MG-SI合金 第一性原理计算 时效析出相 形成焓 电子态密度 

分 类 号：TG146.2[一般工业技术—材料科学与工程]