稀土元素Gd、Nd对AZ80镁合金组织和力学性能的影响

通过金相、扫描电镜、电子探针和力学性能测试等方法研究了稀土元素Gd和Nd对AZ80镁合金铸态和挤压态组织和力学性能的影响。结果表明,适当添加稀土元素可以使AZ80镁合金的铸态树枝晶基本消失,晶界处层片状Mg17Al12相增多。均匀化后晶粒尺寸明显减小。合金经挤压后均发生了动态再结晶,动态析出的β相沿着再结晶晶粒的晶界分布。加入2%RE(Gd,Nd)后,析出相阻碍再结晶晶粒长大和粒子激发形核再结晶共同作用起到了细晶强化的效果,且高硬质Al2Gd和Al2Nd相能有效阻碍位错运动从而大幅度提高了合金的屈服强度。随着RE(Gd,Nd)含量的增多,β相析出减少,稀土相颗粒变大,弱化了动态再结晶效果,导致应力集中,强度下降。当加入2%RE(Gd,Nd)时其抗拉强度最大,综合性能较好。     

稀土元素在医用镁合金中应用的研究进展

由于良好的生物相容性,镁合金成为近来研究的热点医用合金,但是较低的耐蚀性制约了其应用的广泛性。稀土元素由于独特的结构,在改善合金组织及性能方面有着重要的作用。简述了稀土元素在镁合金应用中的优势,介绍了稀土元素对生物医用镁合金的组织、力学性能和耐蚀性能的影响以及其作为植入材料植入人体后细胞的毒性反应,并展望了稀土元素在医用镁合金方面的应用前景和发展方向。     

医用镁合金:成分、组织及腐蚀

镁合金具有良好的生物相容性和力学相容性,具有发展成为新一代可降解生物材料的前景。本文总结了医用镁合金合金化的原理与进展,分析了合金元素对镁合金材料学以及生物学性能的影响,重点讨论了医用镁合金显微组织(晶粒尺寸、第二相、长周期堆垛有序相(LPSO)、准晶相)、热处理和表面氧化膜对其降解行为的影响和腐蚀形态、机理方面的重要进展,并指出了医用镁合金的发展方向。     

新型稀土镁合金的研究进展

稀土镁合金因其优异的室温及高温力学性能而具有广阔的发展前景,文中详细介绍了稀土镁合金中稀土元素在铸造性能、微观组织、力学性能和耐蚀性能方面的作用,以及Mg-Y和Mg-Gd两大主要稀土镁合金系的发展现状。重点分析了目前的研究热点之一:长周期有序结构LPSO(Long Period Stacking Ordered Structure),并针对Mg-Y(-RE)-Zn和Mg-Gd(-RE)-Zn两个合金系的研究现状进行了阐述;如何提高稀土镁合金的强度、韧性、高温性能和耐蚀性能等方面的同时,解决高成本制备和环境污染问题,建立健全一个绿色的稀土镁合金产业链仍需科研工作者的进一步努力研究。     

稀土(Ce、Nd)镁合金的研究现状及进展

镁合金是工程应用中最轻的金属结构材料,具有密度低、比强度高、比刚度高、减振性高等优点,被誉为21世纪绿色工程金属结构材料.稀土元素由于具有独特的核外电子结构,作为一种重要的合金化元素,在冶金、材料领域起着独特的作用,例如净化合金熔体,细化合金组织,提高合金力学性能和耐腐蚀性能等.综述了稀土在镁合金中的行为,介绍了一系列重要的稀土元素对镁合金的组织和力学性能的影响,并对稀土镁合金的发展提出一些展望.     

医用镁合金的生物腐蚀及高分子涂层处理

利用镁及镁合金的易腐蚀性能来发展可生物降解医用金属材料.选用2种商业镁合金,通过对电化学腐蚀性能及生物相容性的研究,得出含稀土元素的镁合金更适合作医用材料;并考察了壳聚糖涂层对镁合金腐蚀性能的影响,表明壳聚糖涂层能够减缓腐蚀速率,并且处理方式不同,影响不同,为稀土镁合金作为可生物降解医用金属支架材料提供了初步的理论基础.     

高强韧镁-稀土系镁合金研究现状及展望

总结了稀土元素在镁合金中的具体作用,并指出稀土元素对镁合金力学性能有较大影响。综述了常见的Mg-RE合金,包括常规合金添加少量稀土、Mg-Nd-Y等常见的耐热镁合金体系以及近年来研究很热的LPSO相镁合金,并分别对其组织和力学性能进行概述。最后针对目前研究高强韧镁合金所存在的难题,提出了合金化、塑性变形和热处理工艺始终是提高镁合金力学性能的主要手段。     

长周期堆垛有序结构增强的超高强度镁合金的研究

通过常规铸造方法取代快速冷却/粉末冶金方法,制备出具有长周期堆垛有序结构的镁合金,并通过热处理和等通道挤压等方法,提高所制备镁合金的力学性能.试验结果表明,采用常规铸造的方法可以得到具有长周期结构的镁合金,其中具有长周期结构的X相对合金的强化起着重要的作用.     

稀土镁合金的研究现状及应用前景

论述了稀土元素的特性及其对镁合金微观组织的影响,介绍了稀土元素在镁合金中的主要作用及稀土耐热镁合金、稀土阻燃镁合金、稀土高强度镁合金、抗蠕变稀土镁合金等的研究和开发现状,展望了稀土在镁合金中的应用前景。     

稀土在镁及镁合金中的应用

稀土以其特殊的物理化学性质在冶金及材料领域有着广泛的应用。本文主要综述了稀土元素在镁及镁合金熔炼过程中除氢、减少氧化夹杂、阻燃的应用,以及稀土元素对镁合金微观组织结构的细化、高温力学性能的改善和耐蚀性能提高等方面的作用和机理。     

Pt-24Ir-RE合金的显微组织与性能研究

通过金相及电子显微镜技术，进行了力学和电学性能实验，研究了添加微量稀土元素La、Sm、Y对Pt-24Ir合金的组织结构与性能的影响。结果表明：稀土元素有效地细化了合金的显微组织结构，并以单质形式均匀析出和弥散分布在合金基体中，从而使合金的综合性能获得改善。     

耐热镁合金的研究现状与发展方向

介绍了耐热镁合金的研究现状。Cu,Ca,Sc,Sr和稀土元素合金化可以改善镁合金的耐热性能。合金化、挤压和半固态加工等热塑性变形技术能促使镁晶胞中的棱柱面（1010^-)和棱锥面（1011^-）参与滑移，提高该类镁合金的力学性能。超塑成型技术是制备高性能耐热镁合金部件的有效途径     

Microalloying Effect of Sn on Phase Transformation During Heat Treatment in Mg–Y–Zn–Zr Alloys

The microstructure and mechanical properties of the as-cast and heat-treated Mg-4.6 Y-2.5 Zn-0.6 Zr-x Sn(x = 0, 0.2 and0.5 wt%) alloys were investigated in this work. The results showed that the eutectics have been refined with 0.2% Sn addition and it has no effect on the phase category of the alloys. However, Sn3 Y5 phase was found in 0.5% Sn-added alloy.After heat treatment at 520 °C, the transformation of the long-period stacking ordered(LPSO) phase takes place in the Mg-Y-Zn-Zr alloy, but the transition is not completed in the alloys containing Sn. In addition, during the heat treatment, the mechanical properties of Sn-free alloys are significantly improved, and the strength of alloys containing Sn does not change much. Through observation and analysis of the microstructure and mechanical properties, it is found that Sn addition hinders the process of a0-Mg ? a-Mg ? 14 H and the process is the key to the transition of 18 H-LPSO to 14 H-LPSO.     

Recent Progress on Corrosion Behavior and Mechanism of Mg–RE Based Alloys with Long Period Stacking Ordered Structure

Metals and Materials International - Mg alloys containing long period stacking ordered (LPSO) structures possess excellent mechanical properties and corrosion resistance, exhibiting great...     

Microstructure and mechanical properties of a compound reinforced Mg95Y2.5Zn2.5 alloy with long period stacking ordered phase and W phase

The microstructure evolution of Mg100-2xYxZnx(x=2, 2.5, 3, 3.5) alloys was investigated. Results show that the Mg100-2xYxZnx alloys are composed of α-Mg, long period stacking ordered(LPSO) phase and eutectic structure phase(W phase), and the Mg95Y2.5Zn2.5 alloy has the best comprehensive mechanical properties. Subsequently, the microstructure evolution of the optimized alloy Mg95Y2.5Zn2.5 during solidification and heat treatment processes was analyzed and discussed by means of OM, SEM, TEM, XRD and DTA. After heat treatment, the lamellar phase 14H-LPSO precipitated in α-Mg and W phase transforms into particle phase(MgYZn2). Due to the compound reinforcement effect of the particle phase and LPSO phase(18R+14H), the mechanical properties of the alloy are enhanced. The tensile strength and elongation of the Mg95Y2.5Zn2.5 alloy is improved by 9.1% and 31.3% to 215 MPa and 10.5%, respectively, after solid-solution treatment.     

挤压比及不同Mn含量对Mg-10Gd-6Y-1.6Zn-xMn镁合金组织性能的影响

通过模铸法制备了Mg-10Gd-6Y-1.6Zn-xMn (x=0.4, 0.8, 1.2, 1.6, 2.0, wt.%)系列镁合金,研究了挤压比及Mn含量对Mg-10Gd-6Y-1.6Zn-xMn镁合金显微组织及室温力学性能的影响。研究结果表明：铸态Mg-10Gd-6Y-1.6Zn-xMn合金经热挤压后,合金中的长周期堆垛有序(LPSO)结构由亚稳的18R结构转变为稳定的14H结构。大挤压比能够显著提高合金的室温力学性能,当Mn含量为0.8%时,未时效态抗拉强度达到386MPa,断后延伸率约为10%。     

稀土元素的热力学特性及在金属基复合材料中的应用

稀土元素具有许多独特的性质，少量稀土元素的存在能极大地影响金属材料的结构与性能，本文在分析稀土元素热力学特性的基础上，从物理化学角度和复合材料结构与性能的关系上，讨论了稀土元素对金属基复合材料的影响，在铝基复合材料中加入Ｌａ系元素后，由于形成Ａｌ－Ｌａ金属间化全物，从而使其耐热性能有明显增加，同时稀土元素的加入也可使Ａｌ基体晶粒细化，使复合材料的综合机械性能得到改善，此外还有提高耐腐蚀性能的效果。     

FeMnCoCr系亚稳高熵合金的研究进展

高熵合金是一种原子排列有序,化学无序的新型多主元合金。通过改变合金元素的种类和浓度,能够调控合金系统层错能及显微组织的相稳定性,进而诱发形变孪晶、马氏体相变等塑性变形机制,最终使合金获得突出的综合力学性能。这种高熵合金的设计理念称为“亚稳工程”。亚稳高熵合金的显微组织、相结构及变形机制与合金体系的层错能密切相关。在FeMnCoCr系亚稳高熵合金中,随着系统层错能降低,面心立方结构稳定性下降,从而激活应变诱导马氏体相变(γ→ε),实现了合金强度和塑性的同时提高。本文主要介绍了FeMnCoCr系亚稳高熵合金的成分设计、制备及加工方法、微观结构和力学性能,并对亚稳高熵合金未来的研究方向进行了展望。     

Recent advances in micro-alloyed wrought magnesium alloys: Theory and design

Micro-alloying design of wrought magnesium (Mg) alloys is an important strategy to achieve high mechanical properties at a low cost. In the last two decades, significant progress has been made from both theory and experiment. In the present review, we try to summarize recent advances in micro-alloying design of wrought Mg alloys from both theoretical and pragmatic perspectives, and provide fundamental data required for establishing the relationship between chemical composition and mechanical properties of Mg alloys. We start with theoretical attempts for understanding the mechanical properties of Mg alloys at different scales, by involving first principle calculations, molecular dynamics, cellular automata, and crystal plasticity. Then, the role of alloying elements is discussed for a series of promising Mg alloys such as Mg-Al, Mg-Zn, Mg-RE (rare-earth element), Mg-Sn, and Mg-Ca families. Potential challenges in the micro-alloying design of Mg alloys are highlighted at the end. The review is expected to provide helpful guidance for the intelligent design of novel wrought Mg alloys and inspire more innovative ideas in this field.     

Microstructure and Mechanical Properties of Mg–RE–TM Cast Alloys Containing Long Period Stacking Ordered Phases: A Review

Casting magnesium alloys hold the greatest share of magnesium application products due to their short processing period, low cost and near net shape forming. Compared with conventional commercial magnesium alloys or other Mg–RE-based alloys, the novel Mg–RE–TM cast alloys with long period stacking ordered(LPSO) phases usually possess a higher strength and are promising candidates for aluminum alloy applications. Up to now, two ways: alloying design and casting process control(including subsequent heat treatments), have been predominantly employed to further improve the mechanical properties of these alloys. Alloying with other elements or ceramic particles could alter the solidifi cation pattern of alloys, change the morphology of LPSO phases and refi ne the microstructures. Diff erent casting techniques(conventional casting, rapidly solidifi cation, directional solidifi cation, etc.) introduce various microstructure characteristics, such as dendritic structure, nanocrystalline, metastable phase, anisotropy. Further heat treatments could activate the transformation of various LPSO structures and precipitation of diverse precipitates. All these evolutions exert great impacts on the mechanical properties of the LPSO-containing alloys. However, the underlying mechanisms still remain a subject of debate. Therefore, this review mainly provides the state of the art of the casting magnesium alloys research and the accompanying challenges and summarizes some topics that merit future investigation for developing high-performance Mg–RE–TM cast alloys.