Er合金化在镁合金中的作用研究进展

介绍了稀土Er在镁合金中的主要作用.稀土Er不仅在镁合金熔炼过程中具有熔体净化和提高阻燃性的作用,还可以有效提高铸态合金力学性能和耐蚀性,合金性能的提高主要是因为稀土Er细化合金晶粒组织,以及改变第二相数量和形态.综述了稀土Er对Mg-A1系和Mg-Zn系镁合金微观组织、力学性能和耐蚀性的影响.     

Mg-Zn合金的时效处理研究进展

镁合金具有密度小、比强度及比刚度高、良好的切削加工性能及易于回收等优点。时效处理是提高镁合金的力学性能常见方法之一。本文基于析出相变理论和Mg-Zn二元相图,对Mg-Zn系二元及多元镁合金在时效处理时可能出现的组织结构变化作出预测。结合文献,探讨了时效处理时GP区的形成组分及温度条件,及其带来的材料力学性能变化,总结了铸态、变形MgZn系合金时效处理最佳工艺。     

稀土元素对SnAgCu系无铅钎料合金组织与性能的影响

研究了不同类型的稀土元素Ce,Er,Y及其用量对Sn0.3Ag0.7Cu系钎料合金熔化温度、润湿性能、力学性能以及微观组织的影响。结果表明:稀土元素对钎料的性能有不同的影响,添加w(Ce)0.10%可有效细化微观组织,提高合金的润湿性和力学性能等综合性能,但稀土Er和Y对钎料性能的影响不太明显。     

高温镁合金的成分、组织设计与制备加工技术进展

介绍了提高镁合金高温性能的主要途径及目前研究较多的Mg-Al系、Mg-Zn系和Mg-RE系合金,同时分析了正在开始研究的含Y、Sc、Gd等稀土的新型耐热镁合金;同时分析了耐热合金中的耐热相,耐热合金的加工制备工艺进展。     

Zr对Mg-Zn合金力学性能及体外降解行为的影响

制备Mg-2.5wt%Zn和Mg-2.5wt%Zn-0.5wt%Zr合金,对其微观组织、力学性能和体外降解行为进行对比.结果表明,Zr元素对Mg-Zn合金的细化作用显著,合金的晶粒尺寸由60 μm减小到20 μm.添加Zr使Mg-Zn合金的强度、塑性和硬度均有所提高,其抗拉强度和伸长率分别达到315 MPa和21.4%.经体外降解测试,Mg-2.5wt%Zn-0.5wt%Zr合金的平均降解速率为3.32 mm/a,其耐蚀性优于Mg-2.5wt%Zn合金.     

Zr对Mg-6Zn-2Y合金组织及凝固行为的影响

Mg-Zn-Y合金组织中由于准晶相的发现受到越来越多的关注。Zr在镁合金中主要起细化晶粒的作用,在Mg-Zn系合金中作用尤为显著。本文通过组织观察和热分析冷却曲线方法研究了Zr的加入对Mg-6Zn-2Y（wt%）合金组织及凝固行为的影响。结果表明,加Zr后,铸态组织明显细化,合金凝固过程也有显著变化。     

含Ⅰ相Mg-Zn-Y合金的高温变形行为和加工图（英文）

通过热压缩试验(温度300~450℃,应变速率0.001~1 s~(-1))研究挤压态含Y元素的Mg-Zn合金的微观组织和力学性能。用热加工图反映合金热变形的最佳条件和非稳定区。Mg-Zn和Mg-Zn-Y合金的峰值应力、温度和应变速率的关系符合双曲正弦函数,激活能分别为177 k J/mol和236 k J/mol。流变应力曲线表明,Y的添加会增加峰值应力并减小峰值应变,且Mg-Zn-Y合金发生动态再结晶所需的应变比Mg-Zn合金的小。Mg-Zn-Y合金的稳定区发生在:1)300℃,0.001 s~(-1);350℃,0.01-0.1 s~(-1)和400℃,0.01 s~(-1);2)450℃,0.01-0.1 s~(-1)。显微组织的观察结果显示,合金中主要的恢复机制是动态再结晶,Mg-Zn-Y合金发生完全动态再结晶的温度为450℃。在高应变速率下,Mg-Zn-Y合金明显形成非稳定区。另外,Mg-Zn和Mg-Zn-Y合金的非稳定区域宽度随应变的增加而增加,这些区域还发生了孪生和严重变形。     

Mg-x％Zn-(Al)合金显微组织及力学性能

利用光学显微镜、X射线衍射仪、扫描电镜和万能力学试验机研究了Mg-x％Zn(5、7、9、15和20％)二元合金和Mg-7Zn-4Al合金的显微组织及力学性能.结果表明:Mg-Zn合金铸态显微组织主要由α-Mg和沿晶界分布的Mg7Zn3共晶相组成.随着Zn含量的增加,Mg-Zn二元合金的抗拉强度呈先上升后下降的趋势,而伸长率呈逐渐下降的趋势.当Zn含量为7％时,合金的抗拉强度达到最大,为213.3 MPa;当Zn含量高于9％后,合金的抗拉强度和伸长率急剧下降.在Mg-7Zn基体合金中添加4％Al后,合金的显微组织主要由oα-Mg和Mg32(Al,Zn)49三元共晶相组成.合金的铸态力学性能相对于基体有所下降,但是热处理后抗拉强度得到显著提高,为305 MPa,相对铸态提高了57.8％.Mg-Zn合金中添加A1元素有利于合金的热处理强化.     

Pt-Ir系掺杂Zr，Mo，Y对合金相性能的影响

在Pt-Ir系中分别加入Zr、Mo、Y三种元素,研究稀有金属元素的加入对Pt-Ir系组织结构及力学和电学性能的影响.合金相在真空高频炉中熔炼.用X射线衍射仪和金相显微镜对合金相的显微组织和结构进行分析,用电桥、涡流导电仪测量合金相的电阻率,用拉力试验机测量合金相的力学性能.结果表明:稀有金属元素的加入可以有效地细化合金相的显微组织,并且提高合金相的熔点、密度、力学性能和电阻率,但是合金相的加工性能有所降低.     

主要合金元素对镁合金组织及耐蚀性能的影响

论述了耐蚀镁合金的研究现状。分类叙述了主要的合金元素(Al,Zn,Mn,Ca,Zr,RE)对几种主要的镁合金系(Mg-Al系合金、Mg-Zn系合金、Mg-RE系合金)微观组织及耐蚀性能的影响。总结了提高镁合金耐蚀性的主要途径,最后指出发展耐蚀镁合金的方向。     

稀土Y和Nd对ZM5合金组织和性能的影响

以ZM5镁合金为基体材料，应用铸造方法制备了4种不同稀土含量和比例的稀土镁合金。考察分析了稀土Y和Nd对ZM5合金组织结构、力学性能和腐蚀性能的影响。结果表明，铸态合金中出现了新相Ti2Mg3Al3，它对于减少晶界处第二相的析出有积极作用。ZM5合金的组织结构、力学性能和腐蚀性能随稀土Y和Nd的比例不同而有比较大的差异，在所有考察的ZM5合金中，添加2％Y和1％Nd稀土的合金综合效果最好。     

Effects of Cu addition on microstructure and mechanical properties of as-cast Mg-6Zn magnesium alloy

The application of Mg-Zn binary alloys is restricted due to their developed dendritic microstructure and poor mechanical properties. In this study, an alloying method was used to improve the mechanical properties of Mg-Zn alloy. The Mg-6Zn magnesium alloys microalloyed with varying Cu content(0, 0.8, 1.5, 2.0 and 2.5wt.%) were fabricated by permanent mould casting, and the effects of Cu content on the microstructure and mechanical properties of as-cast Mg-6Zn alloys were studied using OM, SEM, XRD and tensile tests at room temperature. The obtained results show that the addition of Cu not only can refine the grains effectively, but also can modify the eutectic morphology and improve the mechanical properties of the alloys. The main phases of the studied alloys include α-Mg, MgZn_2, Mg_2Cu and CuMgZn. When the content of Cu exceeds 0.8wt.%, Mg_2Cu phase appears. Meanwhile, the eutectic morphology is modified into dendritic shape or lamellar structure, which has an adverse effect on the tensile properties. Furthermore, among the investigated alloys, the alloy containing 0.8% Cu shows an optimalultimate tensile strength of 196 MPa, while the alloy with 1.5wt.% Cu obtains an excellent elongation of 7.22%. The experimental alloys under different Cu contents show distinguishing fracture behaviors: the fracture of the alloy with 0.8wt.% Cu reveals a mixed mode of inter-granular and quasi-cleavage, while in other investigated alloys, the fracture behaviors are dominated by cleavage fracture.     

Deformation behavior and processing maps of Mg-Zn-Y alloy containing I phase at elevated temperatures

The microstructure and mechanical properties of extruded Mg-Zn alloy containing Y element were investigated in temperature range of 300–450 °C and strain rate range of 0.001–1 s^?1 through hot compression tests. Processing maps were used to indicate optimum conditions and instability zones for hot deformation of alloys. For Mg-Zn and Mg-Zn-Y alloys, peak stress, temperature and strain rate were related by hyperbolic sine function, and activation energies were obtained to be 177 and 236 kJ/mol, respectively. Flow curves showed that the addition of Y element led to increase in peak stress and decrease in peak strain, and indicated that DRX started at lower strains in Mg-Zn-Y alloy than in Mg-Zn alloy. The stability domains of Mg-Zn-Y alloy were indicated in two domains as 1) 300 °C, 0.001 s^?1; 350 °C, 0.01–0.1 s^?1 and 400 °C, 0.01 s^?1 and 2) 450 °C, 0.01–0.1 s^?1. Microstructural observations showed that DRX was the main restoration mechanism for alloys, and fully dynamic recrystallization of Mg-Zn-Y alloy was observed at 450 °C. The instability domain in Mg-Zn-Y alloy was located significantly at high strain rates. In addition, the instability zone width of Mg-Zn and Mg-Zn-Y alloys increased with increasing strain, and cracks, twins and severe deformation were considered in these regions.     

Y对AZ91D镁合金组织及力学性能的影响

研究了稀土元素钇（Y）对AZ91D镁合金铸态及热处理态的组织和力学性能的影响。结果表明：Y会强烈地细化合金组织，并在合金中生成方块状的Al6Mn6Y相及杆状的Al2Y相。少量的Y能显著提高合金的力学性能，当Y含量（质量分数）达到1．5％时，合金得到最佳的力学性能。另外，含Y的AZ91D合金固溶处理后硬度及抗拉强度皆高于原AZ91D合金，并且Y会推迟镁合金的时效过程，延长时效峰值的到来时间。     

富Y重稀土对ZM5合金组织和性能影响的研究

以ZM5镁合金为基体材料，以富Y重稀土为添加原料，应用铸造方法制备了稀土镁合金。利用光学金相显微镜（OM）、X衍射分析、拉伸试验和腐蚀试验等方法，考察分析了稀土Y对ZM5合金铸造组织结构、力学性能和腐蚀性能的影响。结果表明，铸态合金中出现了新相Al3La、MgY，它对于减少晶界处第2相的析出、晶粒的细化以及力学性能的提高起着积极作用。同时，稀土的加入明显地改善了合金的腐蚀性能。     

Fabrication and characterization of cast magnesium matrix composites by vacuum stir casting process

A vacuum stir casting process is developed to produce SiC_p reinforced cast magnesium matrix composites. This process can eliminate the entrapment of external gas onto melt and oxidation of magnesium during stirring synthesis. Two composites with Mg-Al9Zn and Mg-Zn5Zr alloys as matrices and 15 vol.% SiC particles as reinforcement are obtained. The microstructure and mechanical properties of the composites and the unreinforced alloys in as-cast and heat treatment conditions are analyzed and evaluated. In 15 vol.% SiC_p reinforced Mg-Al9Zn alloy-based composite (Mg-Al9Zn/15SiC_p), SiC particles distribute homogenously in the matrix and are well bonded with magnesium. In 15 vol.% SiC_p reinforced Mg-Zn5Zr alloy-based composite (Mg-Zn5Zr/15SiC_p), some agglomerations of SiC particles can be seen in the microstructure. In the same stirring process conditions, SiC reinforcement is more easily wetted by magnesium in the Mg-Al9Zn melt than in the Mg-Zn5Zr melt. The significant improvement in yield strength and elastic modulus for two composites has been achieved, especially for the Mg-Al9Zn/15SiC_p composite in which yield strength and elastic modulus increase 112 and 33%, respectively, over the unreinforced alloy, and increase 24 and 21%, respectively, for the Mg-Zn5Zr/15SiC_p composite. The strain-hardening behaviors of the two composites and their matrix alloys were analyzed based on the microstructure characteristics of the materials.     

Zn-Mg-Ti中间合金对纯镁组织及性能的影响

本文通过模铸法制备了一种Zn-Mg-Ti中间合金,并研究分析了Zn-Mg-Ti中间合金对纯镁显微组织和力学性能的影响。研究结果表明：中间合金主要由基体及“花朵状”Zn-Mg-Ti三元相组成。Zn-Mg-Ti中间合金对纯镁的晶粒组织有显著影响,镁合金晶粒尺寸随中间合金添加量的增大先减小后增大,当中间合金添加量为8%时,镁合金晶粒尺寸最小。镁合金晶粒细化主要归因于Ti原子在固液界面前沿偏聚,造成成分过冷,抑制晶粒长大。对比Mg-6.4wt.%Zn合金和Mg-8（Mg+8wt.%Zn-Mg-Ti中间合金）合金微观组织,发现Ti元素不仅能显著细化Mg-Zn合金晶粒尺寸,而且能够促进M-8合金中的第二相固溶于基体中。挤压态合金力学性能测试结果表明镁合金力学性能随Zn-Mg-Ti中间合金添加量增加先增大后减小,当中间合金添加量为8%时,镁合金综合力学性能最佳,其抗拉强度和延伸率分别为308MPa和21.5%。     

耐热Mg-Zn-Si-Ca合金的显微组织和力学性能

开发了一种新型的Mg Zn Si Ca合金 ,研究了新合金的组织与力学性能之间的关系。研究结果表明 ,Mg 6Zn 1Si合金有较好的综合力学性能。但是由于合金中的主要强化相Mg2 Si呈粗大的汉字状 ,分布于晶界周围 ,在受到应力作用时 ,这种汉字状相与基体的界面处容易产生微裂纹 ,降低合金的抗拉强度、塑性等力学性能。在Mg 6Zn 1Si合金中加入微量Ca后 ,合金的组织得到明显细化 ,并使Mg2 Si强化相形貌由粗大的汉字状转变为细小、弥散分布的颗粒状。由于显微组织的改善 ,使得Mg 6Zn 1Si合金的室温和高温力学性能均有一定的提高     

Zn对Mg-10Gd-2Y-0.5Zr镁合金组织和性能的影响

通过在Mg-10Gd-2Y-0.5Zr合金中添加Zn,采用SEM、XRD及万能拉伸试验机,研究了Zn添加对其铸态组织和力学性能的影响。结果表明,Mg-10Gd-2Y-0.5Zr合金的铸态组织主要由α-Mg、Mg₅(Gd,Y)和Mg₂₄(Y,Gd)5相组成,而添加质量分数为0.5%~1.5%的Zn后,合金的铸态组织主要由α-Mg、Mg₅(Gd,Y,Zn)、Mg₂₄(Y,Gd,Zn)₅及Mg₁₂(Gd,Y)Zn相组成。添加0.5%的Zn后,合金的室温力学性能明显提高,当Zn含量高于1.0%后,镁合金的室温力学性能开始逐步降低。当Zn含量为0.5%时,合金具有较佳的综合力学性能,其抗拉强度、屈服强度和伸长率分别为197 MPa、160 MPa和4.37%。Zn对Mg-10Gd-2Y-0.5Zr合金铸态力学性能的影响与其铸态组织中Mg₅(Gd,Y,Zn)、Mg₂₄(Y,Gd,Zn)₅和Mg₁₂(Gd,Y)Zn第二相及其数量有关。     

Effect of Y on microstructure evolution and mechanical properties of Mg−4Li−3Al alloys

To obtain magnesium alloys with a low density and improved mechanical properties, Y element was added into Mg−4Li−3Al (wt.%) alloys, and the effect of Y content on microstructure evolution and mechanical properties was investigated by using optical microscopy, scanning electron microscopy and tensile tests. The results show that mechanical properties of as-cast Mg−4Li−3Al alloys with Y addition are significantly improved as a result of hot extrusion. The best comprehensive mechanical properties are obtained in hot-extruded Mg−4Li−3Al−1.5Y alloy, which possesses high ultimate tensile strength (UTS=248 MPa) and elongation (δ=27%). The improvement of mechanical properties of hot-extruded Mg−4Li−3Al−1.5Y alloy was mainly attributed to combined effects of grain refinement, solid solution strengthening and precipitation strengthening.