Nd含量对固相合成AZ31-Nd合金显微组织及硬度的影响

稀土Nd对Zn-5％Al合金显微组织和耐蚀性的影响曹祖军;孔纲;车淳山【摘要】The effect of Nd addition on the microstructure of Zn-5％Al alloy was investigated by SEM,EDS,XRD,and the corrosion resistance of the alloy was studied by the polarization curves tests and NSS tests.The results show that the growth of the primary η-Zn phase can be effectively inhibited,and the compact eutectic structure of the alloy can be obtained due to the addition of Nd.The lamellar spacing of eutectic structure of the alloy with the optimal concentration of Nd can be decreased.Nd can be easy to react with Zn and form the intermetallic phase Nd2Zn17 particles in the alloy bath,which will reduce the effective content of element Nd in the alloy bath.The corrosion resistance of the Zn-5％Al alloy will be changed with Nd addition,and the best corrosion resistance of the alloy will be attained when Nd addition is 0.06％.%采用扫描电镜(SEM)、能谱(EDS)和X射线衍射(XRD)研究Nd对Zn-5％Al合金显微组织的影响,采用电化学极化曲线和中性盐雾试验(NSS)研究不同Nd含量对Zn-5％Al合金耐蚀性的影响.结果表明:添加稀土Nd有效抑制初生η-Zn相的生长,显著增加共晶组织比例且组织致密;适量添加稀土Nd,有助于减小共晶组织层片间距.Nd易与Zn形成Nd2Zn17化合物富集在合金底表面,降低Nd的有效含量,减弱Nd的作用.Zn-5％Al合金耐蚀性随着Nd含量变化而变化,当Nd含量为0.06％时,合金的耐蚀性最好.【期刊名称】《中国有色金属学报》【年(卷),期】2017(027)001【总页数】8页(P24-31)【关键词】Zn-5％Al合金;Nd;显微组织;耐蚀性【作者】曹祖军;孔纲;车淳山【作者单位】华南理工大学材料科学与工程学院,广州510640;华南理工大学材料科学与工程学院,广州510640;华南理工大学材料科学与工程学院,广州510640【正文语种】中文【中图分类】TG146.1钢铁在使用过程中易与周围环境介质发生化学和电化学腐蚀，造成功能失效[1]。

河南科技大学硕士学位论文稀土元素Nd、Y和Gd对AZ系镁合金组织和高温力学性能的影响姓名：***申请学位级别：硕士专业：材料学指导教师：***@摘要论文题目：稀土元素Nd、Y和Gd对AZ系镁合金组织和高温力学性能的影响专业：材料学研究生：王小强指导教师：李全安摘要镁合金是最轻的工程结构材料，具有比强度和比刚度高，电磁屏蔽性、减震性和散热性好等优点，以及优异的加工性能和良好的铸造性能。

镁合金材料已被广泛应用于汽车、通讯和航天等相关行业。

但是镁合金的耐热性较差，高温强度、蠕变性能较低。

耐热性差是阻碍镁合金广泛应用的主要原因之一，当温度升高时，镁合金的强度和抗蠕变性能大幅度下降，使它难以作为关键零件（如发动机零件）材料在汽车等工业中得到更广泛的应用。

本文通过合金制备、微观分析和力学性能测试等方法，研究了稀土元素Nd、Y和Gd对AZ91和AZ81镁合金微观组织和高温力学性能的影响。

研究结果表明：适量稀土元素Nd、Y和Gd能够明显细化AZ91和AZ81镁合金的显微组织，提高合金固溶时效状态下的室温和高温强度，合金的延伸率也得到提高。

AZ91镁合金中加入Nd(1-4wt%)后，随着Nd含量的增加，室温和150℃下合金的强度都是先升后降，Nd含量为1%时合金的强度均达到最大值，分别为247MPa和203MPa，比不含Nd的AZ91提高了10.7%和29.3%；Nd含量为2%时，合金在150℃和250℃下的延伸率达到最大，分别是10.48%和13.7%。

AZ81镁合金中加入Y(1-4wt%)，经固溶时效处理后，随着稀土Y含量增加，在室温和150℃下，合金的强度和延伸率基本上呈先升后降的趋势。

当Y含量为2%时合金在室温下的强度和延伸率达到最大，分别为277MPa和11%，与未加Y 的AZ81相比室温强度提高了36.5%。

Y含量为1%时合金150℃下的高温强度和延伸率也达到最大，分别为220MPa和12.4%，与未加Y的AZ81相比高温强度提高了40.1%。

摘要挤压变形AZ31镁合金组织以绝热剪切条纹和细小的α再结晶等轴晶为基本特征。

挤压变形可显著地细化镁合金晶粒并提高镁合金的力学性能。

随挤压比的增大,晶粒细化程度增加,晶粒尺寸由铸态的d400μm减小到挤压态的d12μm(min);强度、硬度随挤压比的增大而增大,延伸率在挤压比大于16时呈单调减的趋势。

轧制变形使板材晶粒明显细化,硬度提高。

AZ31合金中添加Ce,其铸态组织中能够形成棒状Al4Ce相,并能改善合金退火态组织和力学性能;添加Ce可以改善AZ31的综合力学性能。

关键词:AZ31变形镁合金;强化机制；组织；性能绪论20世纪90年代以来,作为最轻金属结构材料的镁合金的用量急剧增长,在交通、计算机、通讯、消费类电子产品、国防军工等诸多领域的应用前景极为广阔,被誉为“21世纪绿色工程材料”,许多发达国家已将镁合金列为研究开发的重点。

大多数镁合金产品主要是通过铸造生产方式获得,变形镁合金产品则较少。

但与铸造镁合金产品相比,变形镁合金产品消除了铸造缺陷,组织细密,综合力学性能大大提高,同时生产成本更低,是未来空中运输、陆上交通和军工领域的重要结构材料。

目前，AZ31镁合金的应用十分广泛,尤其用于制作3C产品外壳、汽车车身外覆盖件等冲压产品的前景被看好,正成为结构镁合金材料领域的研究热点而受到广泛重视。

第1章挤压变形对AZ31镁合金组织和性能的影响1.1 挤压变形组织特征及挤压比的影响作用图1-1为动态挤压变形过程中的组织变化。

动态变形过程大致分为3个区域:初始区、变形区和稳态区，分别对应着不同的组织。

图1-1a为初始区挤压变形前的铸态棒料组织。

由粗大的α-Mg树枝晶和分布其间的α-Mg+Mg17Al12共晶体组成,枝晶形态十分发达，具有典型的铸造组织特征。

晶粒尺寸为112~400μm。

图1-1b为变形区近稳态区组织。

图中存在大量无序流线,流线弯曲度大、方向不定且长短不一，显然这种组织特征是在挤压力作用下破碎的树枝晶晶臂(α固溶体)发生滑移、转动的结果。

稀土元素Nd和Sm对铸造Mg-Zn-Y合金微观组织和力学性能影响的探究摘要：为了探究稀土元素Nd和Sm对铸造Mg-Zn-Y合金微观组织和力学性能的影响，本文以Mg-5Zn-1Y合金为基础，分别添加了0.2%的Nd和Sm稀土元素，并进行了比较分析。

结果表明，添加Nd和Sm后，合金的晶粒尺寸变小，晶界数量增加，断口面积变小，断口形貌更加平滑，且合金强度和塑性均有所提高，其中添加Nd后合金性能改善更为明显。

利用TEM对材料的微结构进行了观察，发现添加稀土元素后出现了更多的内部结构、偏析现象以及亚晶内部的微结构演变。

探究结果表明，添加稀土元素可以显著改善铸造Mg-Zn-Y合金的力学性能和微观组织，其中添加Nd效果更佳。

关键词：稀土元素；Mg-Zn-Y合金；微观组织；力学性能；Nd；SmAbstract: In order to investigate the influence ofrare earth elements Nd and Sm on the microstructureand mechanical properties of casting Mg-Zn-Y alloy,Mg-5Zn-1Y alloy was taken as the basis, and 0.2% of Nd and Sm rare earth elements were added respectively,and compared and analyzed. The results show that after adding Nd and Sm, the grain size of the alloy becomessmaller, the number of grain boundaries increases, the fracture surface area becomes smaller, and thefracture morphology becomes smoother. Moreover, the strength and plasticity of the alloy are both improved, and the effect of adding Nd is more obvious. TEM is used to observe the microstructure of the material,and it is found that more internal structures, segregation phenomena, and microstructure evolution inside the sub-grains appear after adding rare earth elements. The research results show that adding rare earth elements can significantly improve the mechanical properties and microstructure of castingMg-Zn-Y alloy, and the effect of adding Nd is better.Keywords: Rare earth elements; Mg-Zn-Y alloy; Microstructure; Mechanical properties; Nd; SmRare earth elements (REEs) have been widely used as alloying elements in various metal systems due totheir unique properties such as high melting points, high strength, and excellent corrosion resistance. In the case of Mg-Zn-Y alloy, the addition of rare earth elements can significantly improve its mechanical properties and microstructure.The microstructure analysis of the Mg-Zn-Y alloy reveals that the addition of rare earth elements leadsto the formation of more internal structures, segregation phenomena, and microstructure evolution inside the sub-grains. This phenomenon is attributed to the influence of rare earth elements on the crystallographic structure of Mg-Zn-Y alloy which results in the formation of more dislocations and defects. As a result, the mechanical properties of the alloy are improved.The research results indicate that the effect of adding Nd is better than that of adding Sm. This may be due to the fact that Nd has a stronger influence on the formation of internal structures and the segregation phenomenon in the alloy. The improvementin the mechanical properties of the Mg-Zn-Y alloy with the addition of rare earth elements is mainly attributed to the improvement in the strength and ductility of the alloy.In conclusion, the addition of rare earth elements is an effective way to improve the microstructure and mechanical properties of casting Mg-Zn-Y alloy. Specifically, the addition of Nd can lead to better results in terms of microstructure and mechanical properties. These findings are significant for the development of Mg-Zn-Y alloy with enhanced properties for potential industrial applicationsFurthermore, there are still some challenges that need to be overcome in the production and application of Mg-Zn-Y alloys. One of the challenges is the cost of rare earth elements, since they are relatively expensive compared to other alloying elements. Therefore, it is important to develop cost-effective methods to produce Mg-Zn-Y alloys without compromising their quality and properties.Another challenge is the lack of standardization in the production and characterization of Mg-Zn-Y alloys. This can lead to variations in their properties and make it difficult to compare different studies. Therefore, it is important to establish standardized methods for the production and characterization of Mg-Zn-Y alloys, which can facilitate their use in various applications.In addition, the corrosion resistance of Mg-Zn-Yalloys is an important consideration for their application in various industries, including automotive and aerospace industries. Although the addition of rare earth elements can improve the corrosion resistance of Mg-Zn alloys, further research is needed to understand the underlying mechanisms and to develop strategies to optimize their corrosion resistance.In conclusion, Mg-Zn-Y alloys with improved microstructure and mechanical properties can be produced by the addition of rare earth elements, especially Nd. The development of Mg-Zn-Y alloys has great potential for various industrial applications, but there are still some challenges that need to be addressed, including the cost of rare earth elements, standardization in production and characterization, and optimization of corrosion resistance. Future research in these areas will help to overcome these challenges and unlock the full potential of Mg-Zn-Y alloysAnother area of potential research in Mg-Zn-Y alloys is their mechanical and physical properties under extreme conditions. Mg-Zn-Y alloys have been reported to have good mechanical properties at both room temperature and elevated temperatures, making them promising for high-temperature applications in industries such as aerospace and automotive engineering. However, it is important to investigate the effect of exposure to extreme conditions such as high pressure, high temperature, and radiation on the properties of these alloys.Furthermore, there is a significant need for researchon the use of Mg-Zn-Y alloys in biomedical applications. Magnesium alloys, in general, have good biocompatibility and biodegradability, which make them attractive for use in implants and medical devices. However, the high reactivity of Mg-Zn-Y alloys could pose challenges in biological environments. Further research could explore ways to mitigate the reactivity of these alloys and optimize their biocompatibilityfor use in biomedical applications.In conclusion, Mg-Zn-Y alloys show great potential for various industrial applications due to their unique combination of mechanical, physical, and biological properties. However, there are still challenges that need to be addressed, including the cost of rare earth elements, standardization in production and characterization, optimization of corrosion resistance, investigation of properties under extreme conditions, and optimization of biocompatibility for use in biomedical applications. Addressing these challenges through future research will help to unlock the full potential of Mg-Zn-Y alloys and enable their widespread industrial useIn conclusion, Mg-Zn-Y alloys have shown greatpotential for industrial applications due to their desirable mechanical, physical, and biocompatibleproperties. Further research is needed to overcome challenges such as cost of rare earth elements, standardization in production and characterization, optimization of corrosion resistance, investigation of properties under extreme conditions, and optimization of biocompatibility. Addressing these challenges will help to unlock the full potential of Mg-Zn-Y alloys and accelerate their industrial implementation。