机械合金化制备形状记忆合金的研究

机械合金化技术(MA)是一种制备材料的新工艺,用它可以制备性能优越的形状记忆合金.综述了机械合金化技术在TiNi、Cu-Al-Ni、Cu-Zn-Al、Cu-Al-Nb等形状记忆合金制备上的研究状况.     

机械合金化的原理及在磁性材料研究中的应用

介绍了机械合金化的原理和描述机械合金化过程的理论模型。综述了机械合金化在磁性材料研究中的应用，并对目前研究中的存在的问题及发展前景进行了分析。     

描述机械合金化过程的理论模型

本文综述了几种重要的描述机械合金化（ＭＡ）过程的理论模型。这些模型分析了机械合金化过程中球的机械运动，以及粉末在碰撞时的变形、断裂和焊合，碰撞能量的转化和粉末温升等重要问题，在一定程度上反映机械合金化过程的趋势。     

描述机械合金化过程的理论模型

本文综述了几种重要的描述机械合金化过程的理论模型，模型分析了机械合金化过程中球的机械运动，以及粉末在碰撞时的变形，断裂和焊合，碰撞能量的转化和粉末温升等重要问题，在一定程度上反映机械合金过程的趋势。     

机械合金化过程中六方相晶格畸变特点的研究

通过分析球磨试样和球磨后退火试样的Ｘ射线衍射谱，研究了Ｔｉ，Ａｌ混合粉末机械合金化过程中六方相α－Ｔｉ和Ｔｉ３Ａｌ的晶格畸变特点。结果表明，六方相畸变特点为晶体常数减小和ｃ，ａ轴比值ｃ／ａ减小，其中α－Ｔｉ的（０１１１）面和Ｔｉ３Ａｌ的（２０２１）面原子错排最为严。讨论了位错滑移系统和空穴的引入与晶格畸变特点的联系。     

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。     

机械合金化过程中粉末变形与形成复合粉的工艺条件

本文将镍与钛单质混合粉在搅拌式高能球磨机中球磨。采用电子探针研究了粉末组织随球磨时间的变化。测定了了片状粉末的厚度以及复合粉分数随球磨时间的变化，并根据粉变形模型研究了球磨时形成复合粉所需时间与工艺条件的关系。     

机械合金化与材料开发

INCO公司Benjamin于1970年首先提出了用机械合金化方法制取弥散强化型合金粉末。这种方法,在80年代得到了进一步发展,它不仅用于通常的微粉加工,而且扩大到非晶形成及纳米级超细结构材料的研究领域,成为一种前途广阔的新材料制备技术。顾名思义,机械合金化是靠球磨装置将粗颗粒粒子破碎、粘着等机械作用,达到合金化目的。粉碎机械是在工业中最早应用的     

Characterization of Al/SiC Nanocomposite Prepared by Mechanical Alloying Process Using Artificial Neural Network Model

An artificial neural network model was developed for modeling of the effects of mechanical alloying process parameters including milling time, milling speed, and ball-to-powder weight ratio on the crystallite size and lattice strain of the aluminum for Al/SiC nanocomposite powders. A Multilayer Perceptron (MLP) and Radial Basis Function (RBF) networks were used. It was found that MLP network yields better results compared to RBF network with a high correlation coefficients. The neural network model in agreement with other experimental results and theories was shown the variations of the crystallite size and lattice strain of the aluminum against the process parameters.     

Ti-Al混合物粉末在机械合金化过程中的固态相变

本文通过 x 射线和电子显微镜方法研究了 Ti-50at%Al 混合物在机械合金化过程中的固态相变。研究发现:该混合物在研磨的过程中首先发生非晶化,然后,形成的非晶又发生晶化,生成 Ti—Al金属间化合物。在随后的研磨过程中,生成的金属间化合物又发生向非晶的转变。在混合物向非晶的转变过程中,Al 原子向 Ti 的晶格中扩散。因此,机械合金化过程中的非晶化可能是一种复合机制。     

Mechanically activated combustion synthesis of Ti3AlC2/Al2O3 nanocomposite from TiO2/Al/C powder mixtures

Ti₃AlC₂/Al₂O₃ nanocomposite powder was synthesized by mechanical-activation-assisted combustion synthesis of TiO₂, Al and C powder mixtures. The effect of mechanical activation time of 3TiO₂-5Al-2C powder mixtures, via high energy planetary milling (up to 20?h), on the phase transformation after combustion synthesis was experimentally investigated. X-ray diffraction (XRD) was used to characterize as-milled and thermally treated powder mixtures. The morphology and microstructure of as-fabricated products were also studied by scanning electron microscopy (SEM) and field-emission gun electron microscopy (FESEM). The experimental results showed that mechanical activation via ball-milling increased the initial extra energy of TiO₂-Al-C powder mixtures, which is needed to enhance the reactivity of powder mixture and make it possible to ignite and sustain the combustion reaction to form Ti₃AlC₂/Al₂O₃ nanocomposite. TiC, AlTi and Al₂O₃ intermediate phases were formed when the initial 10?h milled powder mixtures were thermally treated. The desired Ti₃AlC₂/Al₂O₃ nanocomposite was synthesized after thermal treatment of 20?h milled powder and consequent combustion synthesis and FESEM result confirmed that produced powder had nanocrystalline structure.     

High Temperature Mechanical Properties of Ni-Al-Cr Based Alloys for Advanced Die-Materials Applications

In this study, we report on advanced Ni3Al based high temperature structural alloys with Zr and B addition in order to apply in the fields of die-casting and high temperature press forming as die materials. Microstructures and mechanical properties of Ni3Al based intermetallic alloys produced by vacuum arc melting were investigated in terms of phase analysis by using a scanning electron microscope （SEM） equipped with an X-ray energy dispersive spectrometer （EDS）, an X-ray diffractometer （XRD） and tensile test. The duplex microstructural feature consisting of γ＇ matrix phase and small intermetallic dispersoids was observed to be distributed over the whole microstructure. The ultimate tensile strength of the present alloy was superior to commercial iron-based and Ni-based die-materials especially in the high temperature region.     

Consolidated Al/Al2O3 Nanocomposites by Equal Channel Angular Pressing and Hot Extrusion

This work is aimed at producing Al-matrix nanocomposites through the powder metallurgy (PM) process. An initial study on pure aluminum powder was performed to analyze the performance of different PM techniques. In particular, Al powder was refined via high-energy ball milling and consolidated by hot extrusion and equal channel angular pressing. The latter revealed to be a very efficient procedure for powder compaction (high density and hardness of the products) and it was adopted for the production of Al-based composites reinforced with 2% and 5 wt% of Al₂O₃ nanoparticles. The composites exhibited higher hardness than the pure aluminum sample.     

Study of Milling Time and Process Control Agent on W–Mo–Cr Pre-Alloying Powders

According to the experimental researches of dynamic friction polishing (DFP) technology, high density and hardness W–Mo–Cr alloy with strong graphitization ability of diamond can achieve a high material removal rate of diamond. In the preparation process of polishing plate, mechanical alloying (MA) method is used to synthetize pre-alloying powders by means of fierce mechanical action and supersaturated solid state reaction performed by high-energy ball milling. The effect and progress of MA are directly affected by the process parameters of ball milling. This article mainly summarizes the microstructural changes of W–Mo–Cr pre-alloying powders varying with milling time and process control agent (PCA) content, and their function mechanisms and potential causes are discussed. The reasonable process parameters of ball milling are optimized by single-factor experiments. The results show that under the conditions of 300 rpm rotation speed, 60 h milling time, and 10% PCA content, the surface activities, compositional uniformity, and grain refinement level of powders are heightened. The preparation of excellent pre-alloying powders provides early technical guarantee for the study of high density tungsten-based alloy used for DFP diamond.     

机械合金化过程中的固态相变

机械合金化是７０年代初发展起来的一种合成材料新工艺。由于用此工艺已经制备出了许多新材料，同时又提出了许多理论问题，因而引起了冶金学家和物理学家的重视。本文综合评述了这一 发展，应用及所涉及的理论，同时对其应用前景进行了探讨。     

Mechanical Properties on Ni3 Al Intermetallic Compound-SiC Composite Material Generated by SHS Method

0 Introduction The Ni3 Al intermetallic compound is of great interest because of its corrosion-resistance, and high melting point. However, it is difficult to make the intermetallic compound using the ordinary method.