X射线衍射技术在材料分析中的应用

X射线衍射分析技术是一种十分有效的材料分析方法,在众多领域的研究和生产中被广泛应用。介绍了X射线衍射的基本原理,从物相鉴定、点阵参数测定、微观应力测定等几方面概述了X射线衍射技术在材料分析中的应用进展。     

Optimization of spark alloying operating parameters of tribosystem parts

The paper presents the results of optimized studies of the processing parameters of steel surfaces by electro-spark alloying. It is shown that with increasing capacitor capacitance with simultaneous voltage reduction between the alloying electrode and the surface treated, the adhesive constituent of the friction force decreases. A relationship is found between the alloying energy parameters and the physico-mechanical and tribological properties of the treated part surface layers.     

Crystallographic Characteristic of Intermetallic Compounds in Al-Si-Mg Casting Alloys Using Electron Backscatter Diffraction

The Al-Si-Mg alloy which can be strengthened by heat treatment is widely applied to the key components of aerospace and aeronautics. Iron-rich intermetallic compounds are well known to be strongly influential on mechanical properties in Al-Si-Mg alloys. But intermetallic compounds in cast Al-Si-Mg alloy intermetallics are often misidentified in previous metallurgical studies. It was described as many different compounds, such as AlFeSi, Al8Fe2Si, Al5(Fe, Mn)3Si2 and so on. For the purpose of solving this problem, the intermetallic compounds in cast Al-Si alloys containing 0.5% Mg were investigated in this study. The iron-rich compounds in Al-Si-Mg casting alloys were characterized by optical microscope(OM), scanning electron microscope(SEM), energy dispersive X-ray spectrometer(EDS), electron backscatter diffraction(EBSD) and X-ray powder diffraction(XRD). The electron backscatter diffraction patterns were used to assess the crystallographic characteristics of intermetallic compounds. The compound which contains Fe/Mg-rich particles with coarse morphologies was Al8FeMg3Si6 in the alloy by using EBSD. The compound belongs to hexagonal system, space group P2m, with the lattice parameter a=0.662 nm, c=0.792 nm. The β-phase is indexed as tetragonal Al3FeSi2, space group I4/mcm, a=0.607 nm and c=0.950 nm. The XRD data indicate that Al8FeMg3Si6 and Al3FeSi2 are present in the microstructure of Al-7Si-Mg alloy, which confirms the identification result of EBSD. The present study identified the iron-rich compound in Al-Si-Mg alloy, which provides a reliable method to identify the intermetallic compounds in short time in Al-Si-Mg alloy. Study results are helpful for identification of complex compounds in alloys.     

Diffraction effects and inelastic electron transport in angle‐resolved microscopic imaging applications

We analyse the signal formation process for scanning electron microscopic imaging applications on crystalline specimens. In accordance with previous investigations, we find nontrivial effects of incident beam diffraction on the backscattered electron distribution in energy and momentum. Specifically, incident beam diffraction causes angular changes of the backscattered electron distribution which we identify as the dominant mechanism underlying pseudocolour orientation imaging using multiple, angle‐resolving detectors. Consequently, diffraction effects of the incident beam and their impact on the subsequent coherent and incoherent electron transport need to be taken into account for an in‐depth theoretical modelling of the energy‐ and momentum distribution of electrons backscattered from crystalline sample regions. Our findings have implications for the level of theoretical detail that can be necessary for the interpretation of complex imaging modalities such as electron channelling contrast imaging (ECCI) of defects in crystals. If the solid angle of detection is limited to specific regions of the backscattered electron momentum distribution, the image contrast that is observed in ECCI and similar applications can be strongly affected by incident beam diffraction and topographic effects from the sample surface. As an application, we demonstrate characteristic changes in the resulting images if different properties of the backscattered electron distribution are used for the analysis of a GaN thin film sample containing dislocations.     

基于X射线衍射线形分析的铝合金切削表层晶体特征研究

为深入研究高速高效加工条件下材料表层晶体特征形成机理,提高铝合金构件服役性能,同时解决传统观察法较难得出晶粒尺寸与位错密度统计学规律的问题,立足微观,以铝合金7050-T7451为研究对象,将材料学与物理学中基于X射线衍射线形分析的Modified Warren-Averbach和Modified Williamson-Hall方法引入切削加工表层微观组织分析中,实现了不同切削速度下切削表层微观组织结构的定量研究。研究表明,高速切削条件下已加工表面以刃位错为主,得出了位错密度值（高达1015m-2以上）与位错密度变化规律,并从塑性变形及能量角度解释了其形成机理;拟合出了晶粒尺寸分布曲线,并通过分布函数分析了已加工表面晶粒分布均匀性;当切削速度高于4500m/min时可以得到位错密度相对较低、晶体尺寸较均匀的已加工表面。     

X光衍射仪样品台维修实例

本文研究了X射线衍射仪的样品台的工作原理与机械结构设计。首先检查并且分析了发生故障的原因。此次故障主要是由于润滑油枯竭导致设备轴承锈蚀所造成的。然后通过对样品台构造的分析,成功的拆卸并且修复了样品台,清洗了样品台中锈蚀的滚子轴承,清除了进一步锈蚀的隐患。此次维修为X射线衍射仪的维修积累了宝贵的经验,保证了学校的科研与教学工作顺利进行。     

显微观察手段在机械摩擦磨损研究中的应用

选择机械零件常用的材料作为试样,在M-200型磨损试验机上对试样进行摩擦磨损试验。试验后对试样进行一系列处理后,用L2003A型金相显微系统和S-570型扫描电镜仪对试样进行金相组织观察和表面扫描,从而研究材料的磨损和显微表面变化的机理。试验结果表明：试样表面有颗粒脱落,某些试样表面有微小固相焊合点,磨损恶劣部位表面的金相组织发生变化;试样摩擦磨损后的表面形貌大部分主要表现为摩擦磨损造成的划痕和擦伤。     

X射线衍射仪数据控制器主控模块设计

X射线衍射仪数据控制器噪用了多CPU总线系统集成技术，是一个多CPU系统控制器，每个CPU控制一个模块，每一个模块都是一个独立的计算机系统，各个系统之间靠底板上的总线连接在一起。     

Research and application of methods of technical diagnostics for the verification of the design node

Research and application of selected diagnostic methods for assessing the condition of the gearbox of machining center accrued from collaboration applied between our work location and the company Regada, Ltd. Prešov. The requirement of our partner was directed to identify the current state of the abrasive particles in oil, to assess the condition of the contact surfaces in the running-in period and to assess the condition of the lubricant. Implemented analysis of gear oils have been prefentially oriented to identify the wear particles produced during running-in period and in the first hours of operation of contact surfaces. At the same time the correlation between total content of Fe (iron) particles in oil and accrual of kinematic will in tooth meshing of toothed ring of the gearbox was monitored. In quantification of the content of ferrous wear particles the impact of the running-in processes on the contact surfaces (bearings, toothing), which can cause negative side effects, was assessed.     

等离子体诊断用成像型软X射线三色谱仪设计

围绕激光惯性约束聚变研究中内爆靶丸的辐射流诊断需求,设计了一种兼顾空间成像功能的三色软X射线谱仪。该谱仪的设计中心能点为210eV、680eV和800eV,能谱分辨率E/ΔE为5~10。采用X射线掠入射光学结构,实现了三个能点的一维聚焦成像,在1mm视场内空间分辨率优于10μm。采用X射线周期多层膜,获得了三个能区的能谱响应,多层膜测试结果满足设计要求。以光学设计和多层膜为基础,建立了系统的光线追迹模型,分析了可控的空间位置误差和瞄准误差对系统光谱分辨和空间分辨的影响,为装调方案及瞄准方法设计提供了精度依据。该谱仪与条纹相机结合,可用于我国强激光装置上的等离子体诊断实验。     

X射线衍射仪故障与维修实例

本文研究了X射线衍射仪的样品台的驱动原理与机械结构设计。通过对设备构造的分析,成功的更换了X射线衍射仪的主机电源,更换了L6202电机驱动模块,修复了控制样品台Y轴电机的驱动电路。最后排除了导致设备短路的故障点。此次维修为大型仪器设备的维护积累了宝贵的经验。     

Effect of nickel nanopowder on lubrication behaviour of low-temperature grease in steel-steel tribosystem

ABSTRACT

Nickel nanoparticles with sizes from 12 to 34?nm were obtained by pyrolysis of nickel formate. They have been used as additives to the low-temperature grease (CIATIM-201). Studies of tribotechnical properties have shown that the CIATIM-201 with nickel additives at concentrations of 0.05 wt. % - 0.2 wt. % has the best antiwear and extreme pressure properties in comparison with pure grease. Friction surfaces were characterised by the methods of atomic-force microscopy AFM (PHYWE), 3D optical microscopy and indentation tests. The improvement of tribotechnical properties of grease is related to the process of micro-polishing, which leads to the formation of a structural layer with a high modulus of elasticity on the friction surface.     

Tool Wear Prediction and Surface Improvement in Vibration Cutting

Prolongation of tool life in metal cutting is an effective factor to produce lower cutting forces and better machined surfaces. In this study, the influence of ultrasonic vibration is analyzed using experimental and numerical methods. Accordingly, turning tests are carried out on an AISI 4140 steel bar in two types of machining: conventional and ultrasonic-assisted turning. After verification of the developed model, tool wear results are discussed with respect to analysis of heat and stress distributed on tool faces. Finally, it was revealed that periodic movement of the cutting tool in vibratory turning resulted in reduced contact time, resulting in lower heat conduction from the deformed chip to tool rake face. As a result, lower wear has been propagated on tool faces compared to a tool worn in conventional turning. In addition, the effect of cutting parameters on surface roughness is investigated by measurement and 3D analysis of surface topography.     

沟槽形表面织构对摩擦噪声的影响

用电加工方法在制动盘蠕墨铸铁材料表面加工出沟槽形表面织构(沟槽深度为30μm、宽度为150μm、间距为500μm),采用球—平面接触方式,选取直径为10mm的Si3N4球为对磨副,对沟槽形织构表面和光滑表面进行了摩擦噪声对比试验,研究了沟槽形表面织构对界面摩擦振动噪声的影响。试验结果表明(以下结论只针对本试验选定尺寸规格的沟槽形表面织构):法向载荷对织构表面产生摩擦噪声强度的影响较小,而对光滑表面产生摩擦噪声的水平具有重要影响;沟槽形织构表面在低法向载荷下较光滑表面更易产生摩擦噪声,但随着法向载荷从5N增大到10N,光滑表面产生的摩擦噪声强度迅速增大并与织构表面的接近;沟槽形表面织构使摩擦系统更易产生多频率的摩擦振动,较早地产生摩擦噪声且其主频率成分较复杂;沟槽形织构表面比光滑表面具有较高的摩擦因数和耐磨性,沟槽形织构的存在明显地改变了接触界面摩擦磨损行为和摩擦噪声特性,但其对应关系需要进一步深入研究。     

不同介质下ER8车轮钢滑动摩擦磨损性能

为探讨车轮在不同环境下服役时摩擦因数的变化机制,通过滑动摩擦试验机考察不同载荷下,ER8车轮钢分别在干燥空气、纯水、3.5%氯化钠溶液3种环境下的摩擦磨损性能。利用光学显微镜、扫描电子显微镜、非接触三维表面轮廓仪、X射线衍射仪对磨痕及元素组成进行了分析,探讨不同环境下ER8车轮钢的摩擦磨损机制。结果表明：随着载荷的增大,ER8车轮钢的摩擦因数明显增大;列车的服役环境对车轮的摩擦磨损性能有较大影响,在干燥空气环境下,ER8车轮钢无腐蚀状况,磨痕宽度最小,但摩擦因数最大,可达0.503;在盐水环境下,ER8车轮钢出现腐蚀现象,磨痕宽度最大,但摩擦因数最小;干摩擦下ER8车轮钢的磨损机制为黏着磨损、磨粒磨损和氧化磨损,纯水摩擦和3.5%NaCl溶液环境下的磨损机制为磨粒磨损和氧化磨损。     

晶体取向显微成像的应用

扼要介绍LINK OPAL电子背散射衍射技术中的一种全新的图像--晶体取向显微成像图,并讨论晶体取向显微成像技术在钢铁材料研究中的应用。     

Sliding friction and wear of magnesium alloy AZ91D produced by two different methods

Alloy AZ91D is a leading magnesium alloy used for structural applications. It contains aluminum and zinc as principal alloying elements. This alloy is normally die-cast, but recent developments in semi-solid injection molding (Thixomolding^®), which offers certain processing advantages, produces a slightly different microstructure than die-casting, and it was of interest to determine whether the two processing routes would measurably affect the friction and wear of AZ91D. The present work involved ambient air, room temperature testing of die-cast (DC) and Thixomolded^® (ThM) AZ91D, in both unidirectional and reciprocating sliding motion, using stainless steel type 440C as the counterface. After running-in, the average sliding friction coefficients in both types of test fell into the range of 0.29–0.35, irrespective of processing method. The formation of a built-up edge raised the friction slightly in unidirectional tests compared with reciprocating tests. The average wear rate of the ThM alloys in reciprocating sliding was approximately 25% lower than that for DC alloys. However, the wear rates of the magnesium specimens in unidirectional sliding were comparable for DC and ThM materials. Owing to the transfer of magnesium, there was no measurable wear on the stainless steel 440C balls. The wear mechanism during sliding involves the formation of thin, narrow shards along the edges of wear grooves which break off to produce loose particles.     

应用X射线衍射法测定轴类工件中的残余应力

根据测试距车轴表面2mm深度处残余应力的要求,推导了剥层测残余应力的修正公式,利用生死单元法模拟了车轴车削的过程,验证了该修正公式的正确性,并采用X射线衍射法测定了距某车轴表面2mm深度处的轴向和周向残余应力。结果表明:X射线衍射法和修正公式能有效测出距车轴表面2mm深度处的残余应力;轴向残余应力最大值(绝对值)和周向残余应力最大值(绝对值)分别出现在0°测点和90°测点,其值分别为-139.15MPa和-105.21MPa,轴向残余应力和周向残余应力各点的差值均小于EN13261标准规定的40MPa。     

同步辐射在生物大分子结构研究中的应用

本文介绍同步辐射X射线衍射技术的特点及其在生物大分子结构研究中的应用