贵金属高温合金的研究现状及展望

简述了目前高温合金材料存在的问题,介绍了贵金属高温合金的主要特点,指出了研究贵金属高温合金的必要性,系统地综述了贵金属高温合金的研究成果、应用及目前存在的主要问题,最后展望了贵金属高温合金的研究方向。     

航空结构材料研究进展

本文对航空系统结构材料的现状和进展，以及先进的材料和工艺对飞机和飞机发动机的进步所起的重要作用进行了全面系统的研究。本文的主要内容是关于航空和航空发动机材料，以及新材料在制造轻型结构中的作用。     

搅动摩擦焊的特点和应用

搅动摩擦焊是在摩擦焊基础上派生出来的，它不受焊件必须是旋转对称体的限制，适于焊铝合金等熔点较低材料，焊缝为固态组织，避免了普通熔焊可能产生的各种缺陷，是解决Ａｌ－Ｌｉ合金，金属基复合材料焊接问题的好方法。     

"绿色”高效Al -Si合金变质剂--Al-P中间合金

为了解决Al-Si变质过程中的环境污染问题,用熔铸法制备了一种高效,低价格且适于产业化生产的Al-Si合金变质剂－Al-P中间合金,该中间合金w(P)可达到2．0％－5．5％,对共晶和过共晶（含Si量12％－24％）成分的Al-Si合金进行变质,加入0．3％－0．8％的Al-3P中间合金即得良好的变质效果,使其初晶Si数量明显增多,平均晶粒尺寸分别下降到30μm和50μm以下,该中间合金使用工艺简便,可在低温下加,而且无污染,无反应渣,变质效果长效稳定,易储存、使用综合成低,克服了当前变质的缺点,可以实现Al-Si合金的“绿色”变质,有着广阔的应用前景。     

大块镁基非晶态合金的研究进展

综述了大块镁基非晶态合金的合金体系、配方、制备方法及其性能的最新研究进展.主要从合金体系发展的历史中总结了合金体系发展的基本线索,认为Mg-TM-Ln体系是大块镁基非晶态合金的最基本体系.最后,介绍了大块非晶态合金的生产和应用现状,展望大块镁基非晶态合金将在3C产品(computer, communication, consumer electronics products)领域有重大发展潜力.     

钛合金的应用和低成本制造技术

钛及钛合金具有优异的综合性能，是一种重要的金属结构材料，在军工、民用各个领域得到广泛的应用。简要阐述了钛合金的应用现状，分析了降低钛合金成本的可能性途径。     

Titanium for aerospace: Rationale and applications

Titanium and titanium alloys are excellent candidates for aerospace applications due to their high strength to weight ratio and excellent corrosion resistance; titanium and its alloys are immune to almost every medium to which they would be exposed in an aerospace environment. Titanium usage is, however, strongly limited by its higher cost relative to competing materials, primarily aluminum alloys and steels. Hence the advantages to using titanium must be balanced against its added cost. The titanium alloys used for aerospace applications, some of the characteristics of these alloys, the rationale for utilizing them, and some specific applications of different types of actual usage will be discussed herein.This is an extension of References 1 and 2, which reviewed applicaiions of alloys. These references will provide more details on applications of the alloys, while the and / alloys are added herein.     

Martensitic transformation and shape memory properties of Ti-Ta-Sn high temperature shape memory alloys

The effects of Ta and Sn contents on the martensitic transformation temperature, crystal structure and thermal stability of Ti-Ta-Sn alloys are investigated in order to develop novel high temperature shape memory alloys. The martensitic transformation temperature significantly decreases by aging or thermal cycling due to the formation of ω phase in the Ti-Ta binary alloys. The addition of Sn is effective for suppressing the formation of ω phase and improves stability of shape memory effect during thermal cycling. The amount of Sn content necessary for suppressing aging effect increases with decreasing Ta content. High martensitic transformation temperature with good thermal stability can be achieved by adjustment of the Ta and Sn contents. Furthermore, the addition of Sn as a substitute of Ta with keeping the transformation temperature same increases the transformation strain in the Ti-Ta-Sn alloys. A Ti-20Ta-3.5Sn alloy reveals stable shape memory effect with a martensitic transformation start temperature about 440 K and a larger recovery strain when compared with a Ti-Ta binary alloy showing similar martensitic transformation temperature.     

难熔高熵合金的研究进展及应用

高熵合金不同于传统工程合金,是由多种元素以等摩尔或近等摩尔的比例混合,形成的以简单固溶体结构为基体的系列成分复杂合金。其中含高熔点元素的难熔高熵合金具有较高的高温强度和优异的高温抗氧化性能及耐蚀性能等突出特点,其潜在的高温应用价值引起了广泛关注。详细阐述了难熔高熵合金的研究现状及应用,根据晶体结构类型将难熔合金体系进行了分类,并对各类体系中的微观组织特征进行了概述;进而归纳总结了难熔高熵合金的各种性能,包括高强度、耐磨性、高温抗氧化性、耐蚀性能等;最后对难熔高熵合金的发展及应用前景进行了展望。     

Effects of Al and Zn additions on mechanical properties and precipitation behaviors of Mg-Sn alloy system

For the Mg-Sn-Al alloys, the ultimate strength (UTS) of an extruded Mg-9wt.%Al-2wt.%Sn alloy reached 390 MPa. TEM observation indicated that plate-like Mg₁₇Al₁₂ precipitates having Burgers orientation relationship with the matrix are responsible for the strength. This alloy also exhibits an age hardening behavior: the peak hardness appears after 15-20 h of heat treatment at 473 K. On the other hand, the UTS of the Mg-Mg-Sn-Zn alloys are on the order of 300 MPa. The precipitates in these alloys are composed of the Mg₂Sn and MgZn₂ particles. It was found that these phases often precipitate together, suggesting that the MgZn₂ phase can act as a nucleation sites for Mg₂Sn.     

生物医学钛合金的研究现状及发展趋势

本文在回顾生物医学钛合金发展历史的基础上 ,综述了国外近年来新开发的生物医学钛合金的组成及性能 ,提出了我国生物医学钛合金的发展方向。     

Machine learning of phases and mechanical properties in complex concentrated alloys

The mechanical properties of complex concentrated alloys (CCAs) depend on their formed phases and corresponding microstructures.The data-driven prediction of the phase formation and associated mechanical properties is essential to discovering novel CCAs.The present work collects 557 samples of various chemical compositions,comprising 61 amorphous,167 single-phase crystalline,and 329 multi-phases crystalline CCAs.Three classification models are developed with high accuracies to category and understand the formed phases of CCAs.Also,two regression models are constructed to predict the hard-ness and ultimate tensile strength of CCAs,and the correlation coefficient of the random forest regression model is greater than 0.9 for both of two targeted properties.Furthermore,the Shapley additive expla-nation (SHAP) values are calculated,and accordingly four most important features are identified.A significant finding in the SHAP values is that there exists a critical value in each of the top four fea-tures,which provides an easy and fast assessment in the design of improved mechanical properties of CCAs.The present work demonstrates the great potential of machine learning in the design of advanced CCAs.     

Progress and Challenge for Magnesium Alloys as Biomaterials

Magnesium alloys are very biocompatiable and show promise for use in orthopaedic implant. Significant progress of research on bioabsorbable magnesium stents and orthopaedic bones has been achieved in recent years. The issues on degradation, hydrogen evolution, and corrosion fatigue and erosion corrosion of magnesium alloys and various influencing factors in simulated body fluid (SBF) are discussed. The research progress on magnesium and its alloys as biomaterials and miscellaneous approaches to enhancement in corrosion resistance is reviewed. Finally the challenges and strategy for their application as orthopaedic biomaterials are also proposed.     

Properties and Structural Changes of Al-3Cu-2Li Alloy after Thermal Treatment

A quantitative evaluation of microstructure and some mechanical properties of Al-3Cu-2Li (wt.%) alloy submitted to solution annealing at 503°C with succeeded age-hardening at three selected temperatures 163°C, 180°C and 190°C for 17 hours were investigated. With increasing the temperature of artificial ageing increases the strength of the alloy and reaches the maximum at 190°C, what is connected with decreasing of the deformation characteristics. Besides precipitates of Al₂Cu and Al₂CuLi the Cu₃Al particles were found.