机械合金化─研制生产金属材料的一种新工艺EI

本文介绍了机械合金化的工艺特点。用机械合金化技术可以获得一些常规方法难以制备的新型合金及难以获得的独特性能，如生产ＯＤＳ合金和弥散强化复合材料，扩大合金元素在基体中的固溶度，获得非晶态合金（金属玻璃），合成金属间化合物材料，获得纳米结构材料。在金属材料研制生产中，机械合金化是一项值得大力研究开发的新技术。     

机械合金化合成的新材料(二)——弥散强化合金、磁性材料、超导合金、金属间化合物及机械化学效应

本文介绍了由机械合金化方法合成的各种新材料——弥散强化材料、磁性材料、超导材料、金属间化合物及机械化学效应的工艺、材料结构、性能特点、机制以及应用状况。认为由机械合金化技术可以获得一些用常规方法难以制备的新型合金及难以获得的独特性能,因而是一项值得大力研究开发的新技术。     

机械合金化的机制

机械合金化是一种制备平衡态和亚稳态材料的新兴技术。机械合金化的热力学与动力学不同于常规的固态反应，而且相转变方式与合金系统及球磨条件密切相关。着重评述了机械合金化过程中非晶态，金属间化合物，过饱和固溶体及纳米晶形成的特点及机制。     

机械合金化非平衡产物

机械合金化是一种非晶平衡态材料制备的新兴技术 ,利用机械合金化技术已制备出各种非平衡态材料 :如非晶、纳米晶、金属间化合物等。文中简要叙述了机械合金化非平衡过程的特点 ,着重介绍机械合金化过程中弥散强化合金、金属间化合物、非晶、纳米晶、过饱和固溶体等非平衡相的形成及其特点 ,提出该技术的开发亟待解决的关键问题     

高能球磨制备非晶态合金研究的进展

本文评述了目前混合基元粉末机械合金化（ＭＡ）及金属间化合物或合金粉末机械研磨（ＭＧ）制备非晶态合金的研究进展，讨论了机械合金化及机械研磨形成非晶态合金的机制。     

机械合金化应用的新领域

本文简述了机械合金过程和原理,着重介绍了机械合金化制备金属间化合物、非晶态合金、TiC的合成及非氧化物弥散强化的工艺、性能特点和机理。认为机械合金化技术有着广阔的前景。     

机械合金化法制备镁基储氢合金的研究进展

机械合金化法是制备镁基储氢合金的较佳工艺。对近年来机械合金化法制备镁基储氢合金的研究开发,特别是在多元合金化、复合储氢合金等方面的发展进行了系统阐述。总结认为,机械合金化法可以显著改善镁基储氢合金的动力学性能和电化学性能,提高储氢量。未来镁基储氢合金应向复合材料、新方法与机械合金化法相结合、材料的计算机设计等方面发展。     

Cu-Cr机械合金化工艺研究进展

综述了机械合金化工艺制备Cu-Cr合金的研究进展。主要包括Cu-Cr机械合金化的基本原理;Cu-Cr粉末机械合金化过程的影响因素,包括球磨时间、球料比,填充率、球磨机转速、过程控制剂、球磨温度等;Cu-Cr合金机械合金化过程的缺陷。简要讨论了机械合金化方法生产Cu-Cr合金粉末的发展前景。     

机械合金化合成Fe-Al系纳米材料研究进展

简述了机械合金化工艺的特点,重点介绍了机械合金化合成Fe-Al过饱和固溶体、金属间化合物、非晶态材料,以及Fe-Al金属间化合物基纳米复合材料的研究进展.并就目前研究的不足及该研究领域的发展方向提出了一些看法.     

机械合金化过程理论模型研究进展

对机械合金化过程理论模型主要模拟方法与结合作了评述。机械合金化过程理论模型大致可分为四类，运动学模型，碰撞模型，能量传输模型与球磨图，温升效应模型，这些模型可在一定范围内预测工艺参数和粉末材料参数对机械合金化过程和结果的影响，有利于机械合金化工艺的优化。     

Metal Alloys for Fusion‐Based Additive Manufacturing

Metal additive manufacturing (AM) is an innovative manufacturing technique, which builds parts incrementally layer by layer. Thus, metal AM has inherent advantages in part complexity, time, and waste saving. However, due to its complex thermal cycle and rapid solidification during processing, the alloys well suit and commercially used for metal AM today are limited. Therefore, it is important to understand the alloying strategy and current progress with materials performance to consider alloy development for metal AM. This review presents the current range of alloys available for metal AM, including titanium, steel, nickel, aluminum, less common alloys (including Mg alloys, metal matrix composites alloys, and low melting point alloys), and compositionally complex alloys (including bulk metallic glasses and high entropy alloys) with a focus on the relationship between compositions, processing, microstructures, and properties of each alloy system. In addition, some promising alloy systems for metal AM are highlighted. Approaches for designing and optimizing new materials for metal AM have been summarized.

     

State of the Art: Applications of Mechanically Alloyed Nanomaterials—A Review

Nanostructured materials as a new class of engineering materials with enhanced properties and structural length scale between 1 and 100 nm can be produced by a variety of different methods. Mechanical alloying (MA) technique is one of the processes to produce nanomaterials. This process involving milling of constituent powder in high-energy ball mills goes extensive mechanical deformation due to ball-powder-ball and ball-powder-container collisions that occur during MA. The development of strong oxide dispersion strengthened (ODS) alloys has been the prime goal of Benjamin's group, which invented the MA technique. But, the possibility of synthesizing a variety of materials has made MA an exciting field to work in for many investigators. Mechanically alloyed nickel-based, iron-based superalloys, and aluminum-based alloys are in commercial production. The ODS Al-base alloys made by MA are found to be much superior to the traditional alloys in term of strength and hardness value even at high temperature. The mechanical alloying process attracts the attention of a large group of researchers and technologists basically because of its potential to produce a variety of materials in the simplest possible way. MA definitely has a bright future as a solid-state processing route.     

Nanostructural materials formation by mechanical alloying: Morphologic analysis based on transmission and scanning electron microscopic observations

The development of nanostructured materials offers new scientific and technological perspectives due to the specific interesting physical properties of these materials. These properties derive either from their reduced grain size or from the structure and properties of the grain boundaries, which constitute a significant volume fraction. Mechanical alloying, widely used to produce dispersion-strengthened and amorphous alloys, has been employed in recent years to synthesize nanocrystalline metallic, semiconductors, and covalent component-based materials. Based on statistical analysis of transmission and scanning electron microscopic images, the distribution and spatial repartition of the nanostructural material prepared by mechanical alloying and/or attrition are presented for some specific cases.     

Mechanical Alloying of Titanium-Base Alloys

Application of mechanical alloying to titanium-base alloys is a recent development. A wide range of terminal phases and those based on titanium aluminides (both Ti₃Al and TiAl) have been examined and it has been shown that synthesis of metallic phases can be achieved by mechanical alloying. The phases so synthesized include solid solutions, intermediate crystalline phases, amorphous phases, and nanostructured materials. It has also been shown that the resistance to coarsening of both the grains and the dispersoids in mechanically alloyed Ti₃Al based alloys is much higher than in rapidly solidified alloys. The review concludes with some thoughts on future developments in this exciting area.     

Enhanced strengthening and hardening via self-stabilized dislocation network in additively manufactured metals

The advent of additive manufacturing (AM) offers the possibility of creating high-performance metallic materials with unique microstructure. Ultrafine dislocation cell structure in AM metals is believed to play a critical role in strengthening and hardening. However, its behavior is typically considered to be associated with alloying elements. Here we report that dislocations in AM metallic materials are self-stabilized even without the alloying effect. The heating–cooling cycles that are inherent to laser power-bed-fusion processes can stabilize dislocation network in situ by forming Lomer locks and a complex dislocation network. This unique dislocation assembly blocks and accumulates dislocations for strengthening and steady strain hardening, thereby rendering better material strength but several folds improvements in uniform tensile elongation compared to those made by traditional methods. The principles of dislocation manipulation and self-assembly are applicable to metals/alloys obtained by conventional routes in turn, through a simple post-cyclic deformation processing that mimics the micromechanics of AM. This work demonstrates the capability of AM to locally tune dislocation structures and achieve high-performance metallic materials.     

Ni-based superalloy surface alloying by double-glow plasma surface alloying technique

The double-glow surface alloying technique, also called the Xu-Tec/Xu-Loy process, is a novel technique in the field of surface alloying. This technique allows alloy layers with unique physical, chemical and mechanical properties, such as nickel-based alloy layers, stainless-steel layers and age-hardened surface high-speed steel layers to be formed at the surface of treated metallic materials. In this paper, recent research of the application of the double-glow plasma surface alloying technique in the formation of corrosion resistance alloy layers is briefly reviewed. The results of a study of Ni-Cr-Mo-Nb and Ni-Cr-Mo-Cu corrosion-resistant alloying layers as well as composite alloying layers with an electric brush plating Ni interlayer are reported.     

稀土镧镁合金的研究进展

镁合金材料被誉为“21世纪绿色工程金属结构材料”,而稀土镧作为一种重要的合金化元素,其具有改善镁合金的铸造性能,显著细化晶粒,提高镁合金力学性能和耐腐蚀性能的作用。本文综述了稀土镧对镁合金显微组织、力学·挂能及耐腐蚀性能的影响。     

High resolution electron microscopy of alloys

High resolution electron microscopy (HREM) has emerged as a very powerful tool for probing the structure of metals and alloys. It has not only helped in unravelling the structure of materials which have been at the forefront of novel materials development such as quasicrystalline phases and high temperature superconducting compounds, but also is fast becoming a technique for solving some outstanding issues in the case of the commercial alloys thereby helping alloy development. In addition to the determination of the structures of phases, this tool is used for obtaining a first hand information of the arrangement of atoms around the various types of crystallographic defects and interphase interfaces. This mode of microscopy allows direct observation of orientation relationships between two phases across interfaces. HREM can be used for the direct examination of the prenucleation process. Initial stages of nucleation can also be studied readily in amorphous alloys, precipitation hardening alloys like maraging steels and in those systems where the formation of the omega phase occurs. This presentation describes some results of HREM studies on various alloys, commercial as well as alloys of scientific interest, where some of the aforementioned aspects have been examined. The specific examples cited pertain to metallic glasses, NiTi shape memory alloys, Ni-Mo, Zr-Nb and Ti-Al alloys.