摘要
Mg-Gd系合金具有质量轻、强度高、耐热性能好等优点,在航空航天领域的应用前景广阔。然而,简单的Mg-Gd二元合金通常重稀土含量很高,综合力学性能也不够完善,已不能满足新型镁合金轻质、高强、低成本的设计理念。为了进一步提升该系合金的性能,迄今已开展了大量研究,主要的改良方案包括:(1)恰当的热处理工艺;(2)必要的变形加工技术;(3)合理的成分优化设计。其中,通过合金化方法不断优化成分配比创造出优良的新型合金是改善Mg-Gd系合金性能的根本方法。鉴于化学成分是影响合金微观组织与力学性能的重要因素,本文综述了合金化元素Ag、Al、Zn、Ca、Si、Mn以及各种稀土元素(RE)对Mg-Gd系合金组织与性能的影响,并展望了其合金化的发展方向。例如,通过添加Zn、Cu、Ni等元素,在保留Mg-Gd系合金中原有纳米级析出相的基础上,还能在组织中形成新的长周期有序堆垛的结构相,从而实现多相协同强化合金的目的。另外,由于稀土元素价格昂贵且不易获得,若能用常见的Al、Mn、Si等非稀土元素代替部分稀土元素,形成新的强化相,则在有效改善合金性能的同时还可降低合金的成本。此外,在合金成分设计上,单一元素的作用效果有限,复合添加才是Mg-Gd系合金化研究的重要发展方向。但需要特别注意的是,在多元化设计过程中某些元素之间因存在相互作用的关系而导致反应失效,例如,含Zr的MgGd系合金一般不添加Al,因为Al不仅能与Zr反应生成Al3Zr相恶化合金组织,而且还会消耗大量基体合金中的稀土元素,降低稀土的利用率。综上所述,在合金化设计过程中,必须解决两大问题:(1)通过合金化元素种类之间的合理搭配,创造出新型合金系列;(2)确定该系列合金中各种元素的最佳含量比,从而使其性能得到进一步优化。本文分析总结了Mg-Gd系合金在合金化方面的研究进展,分别对LPSO形成元素、非LPSO形成元素、稀土金属元素以及非金属元素对Mg-Gd系合金的作用效果进行了讨论,展示了各种元素在该系合金中的研究现状并展望了其应用前景,以期为今后镁合金的合金化设计提供参考。
Thanks to the advantages of light weight,high strength and favorable heat resistance,Mg-Gd alloys owns a wide application prospect in the field of aerospace.Nevertheless,simple Mg-Gd binary alloys often bears a high content of heavy rare earth and unsatisfactory comprehensive mechanical properties,which cannot match the novel magnesium alloy design concept of light weight,high strength and low cost.Up to now,great efforts have been put into the research on further improving the properties of the Mg-Gd alloys.The main improving scheme focus on proper heat treatment process,necessary deformation processing technology,and reasonable composition optimization design.Among them,creating a novel alloy with excellent properties by constant optimization of the composition ratio through alloying is the fundamental method for promoting the performance of Mg-Gd alloy.In view of the fact that the chemical composition is an important factor affecting the microstructure and mechanical properties of the alloy,this paper reviews the effects of alloying elements Ag,Al,Zn,Ca,Si,Mn and diverse rare earth elements(RE)on the microstructure and properties of Mg-Gd alloys,and looks forward to the development direction of alloying.For example,the addition of elements like Zn,Cu,Ni,etc.can contribute to form a new long-cycled ordered stacking structure phase in the structure,while the original nano-precipitated phases in the Mg-Gd-based alloy can still be preserved,thereby achieving the purpose of multi-phase synergistic strengthening of the alloy.Besides,because rare earth elements are expensive and difficult to obtain,if common elements like Al,Mn,and Si can be used as alternatives for rare earth elements to form a new strengthening phase,the alloy performance will be effectively improved and the cost will be reduced.In addition,the effect of single element on the composition of the alloy composition is limited,and compound addition is an important development direction for Mg-Gd alloying study.Whereas special attention should be paid to the fact that interactions between certain elements in the diversified design process may cause the failure of reaction.For example,Al should not be added into Mg-Gd alloys containing Zr generally,because Al element will not only react with Zr to generate Al 3Zr phase to deteriorate the alloy structure,but also consume a large amount of rare earth in the matrix alloy,thus redu-cing the utilization ratio of rare earth elements.To sum up,two major problems must be solved in the alloying design process.Ⅰ.Innovative alloy series should be created through the rational combination of the alloying elements.Ⅱ.The optimal content ratio of various elements in the series of alloys should be determined,so as to further optimize their performance.This article analyzes and summarizes the research progress of alloying in Mg-Gd alloys.The effect of LPSO forming elements,non-LPSO forming elements,rare earth metal elements,and non-metallic elements on Mg-Gd alloys is discussed separately.The research status of various elements in this alloy series is presented and their application prospects are proposed,which is expected to provide reference for the future alloying design of magnesium alloy.
作者
唐昌平
左国良
李志云
孙玹琪
李权
TANG Changping;ZUO Guoliang;LI Zhiyun;SUN Xuanqi;LI Quan(School of Materials Science and Engineering,Hunan University of Science and Technology,Xiangtan 411201;High Temperature Wear Resistant Materials and Preparation Technology of Hunan Province National DefenceScience and Technology Laboratory,Xiangtan 411201;Science and Technology Company Limited of No.608 Research Institute,Zhuzhou 412002;Chongqing Academy of Science and Technology,Chongqing 401123)
出处
《材料导报》
EI
CAS
CSCD
北大核心
2018年第21期3760-3767,共8页
Materials Reports
基金
国家自然科学基金(51605159)
湖南省自然科学基金(2016JJ5042)
重庆市基础科学与前沿技术研究项目(cstc2017jcyjAX0301)
