Fundamentals of nondestructive materials characterization

An attempt is made to outline the term ‘materials characterization’. On the basis of the structure-to-property-relationships, a philosophy is proposed, adapted to systematical development of methods for nondestructive materials characterization. The state of the art reached for metals is reviewed and typical applications of macroscopic physical properties for nondestructive materials characterization are given. The materials characterization of ball bearing steel and cast iron by multiparameter materials characterization is discussed in detail.     

Residual stress characterization in structural materials by destructive and nondestructive techniques

Transmutation of nuclear waste is currently being considered to transform long-lived isotopes to species with relatively short half-lives and reduced radioactivity through capture and decay of minor actinides and fission products. This process is intended for geologic disposal of spent nuclear fuels for shorter durations in the proposed Yucca Mountain repository. The molten lead-bismuth-eutectic will be used as a target and coolant during transmutation, which will be contained in a subsystem vessel made from materials such as austenitic (304L) and martensitic (EP-823 and HT-9) stainless steels. The structural materials used in this vessel will be subjected to welding operations and plastic deformation during fabrication. The resultant residual stresses cannot be totally eliminated even by stress-relief operations. Destructive and nondestructive techniques have been used to evaluate residual stresses in the welded and cold-worked specimens. Results indicate that tensile residual stresses were generated at the fusion line of the welded specimens made from either austenitic or martensitic stainless steel, with reduced stresses away from this region. The magnitude of residual stress in the cold-worked specimens was enhanced at intermediate cold-reduction levels, showing tensile residual stresses in the austenitic material while exhibiting compressive stresses in the martensitic alloys. Comparative analyses of the resultant data obtained by different techniques revealed consistent stress patterns.     

无损检测技术及工业应用综述

无损检测技术是在不损伤被测材料的情况下,检查材料的内在或表面缺陷,或测定材料的某些物理量、性能、组织状态等的检测技术。无损检测技术是一种非常有价值的技术,可以在不破坏待测物质原来的状态和化学性质的情况下进行产品评估、故障诊断和性能研究,既可以节省时间又可以节约成本。因而,无损检测技术广泛用于金属材料、非金属材料、复合材料及其制品以及一些电子元器件的检测。     

Optoelectronic nondestructive testing techniques of cocoon properties and applications

In this paper, cocoon properties are examined, spectral characteristics and mathematical expressions that define cocoon shell's absorption and reflection of light in various wavelengths are obtained and given in graphical form. Finally, optoelectronic methods and systems that determine cocoon properties are designed and explained.     

带极堆焊技术的应用

在承受一定载荷的低碳钢或低合金表面堆焊一层耐蚀层是一种经济、实用的方式。因此,带极堆焊广泛应用于化工、石化和核工业等领域。主要讨论了两种带极堆焊方法,并介绍了这项技术在意大利SICES和Ansaldo Camozzi工厂的应用情况。     

Silicide-matrix materials for high-temperature applications

Intermetallic-matrix composites are attractive alternatives to carbon /carbon and ceramic / ceramic composites for applications up to 1,600°C. Recent work on the intermetallic compounds MoSi₂ and Ti₅Si₃ has included determination of their mechanical properties and deformation behavior, selection of thermodynamically compatible high-strength and ductile reinforcements, and strengthening and toughening mechanisms in silicide-matrix composites for high-temperature service.     

Practical applications of phase diagrams in continuous galvanizing

Zn-Fe based high-order phase diagrams have found a wide range of applications in continuous galvanizing. With the development of computer software DEAL (DetermineEffectiveALuminum), the Zn-rich corner of the Zn-Fe-Al phase diagram is being used daily for scientific interpretation of bath assays. Computer software PAL (PredictAluminumLevel), also developed by Teck Cominco Metals Ltd., assesses transient equilibria between the steel substrate and the liquid galvanizing alloy for the estimation of Fe dissolution and Al consumption in galvanizing. Aluminum deportment in galvanizing baths has been scientifically described based on the fact that bath assays corresponding to different locations and depths of a galvanizing bath formed one tie-line in the liquid-Fe₂Al₅ two-phase field of the Zn-Fe-Al phase diagram. Zn-Fe based high-order phase diagrams also afford a better understanding of the mechanisms for a number of industrial phenomena. These practical applications of the Zn-Fe based phase diagrams are detailed in the article. This article is based on a presentation made at the Galvanizers Association Ninety-Seventh Meeting held in Lexington, KY, from Oct 17 to 19, 2005.     

Titanium composite materials for transportation applications

Discontinuously reinforced titanium alloys containing in-situ formed TiB needles are emerging as candidate materials for advanced applications. This new family of titanium composites presents technical advantages, and it can be less expensive and easily amenable for net-shape manufacturing relative to titanium metal-matrix composites developed to date. The production of a master compound by a novel and cost-effective process called self-propagating high-temperature synthesis (SHS) has been studied. This master compound could be subsequently used in an investment casting process to obtain TiB-reinforced net-shape titanium-matrix composites. The SHS technique and its features were investigated in depth before a suitable master compound was defined and produced. Cast samples obtained from the addition of the master compound have been produced and the most important issues concerning the processing, microstructure, and mechanical properties are highlighted in this paper.     

Thin-film shape-memory materials for high-temperature applications

Many applications of shape-memory alloys (SMAs) are likely to require development of alloys having much higher martensite transformation temperatures than are currently available. This article reviews recent reports on a few promising systems, with emphasis on sputtered films in the NiTiX group. NiTiX is a name for the ternary ordered substitutional solutions of Hf, Zr, Au, Pd, or Pt, in the β-NiTi lattice. These have been the most extensively studied compounds and the only high-temperature SMAs yet fabricated as thin films. For films, the exaggerated kinetics of physical vapor deposition and the generous surfaces of the planar form confer economic and technical advantages, especially in cases involving costly additions or troublesome solidification issues. The outlook for technically useful SMAs operating at up to 240°C is quite good. Operation at temperatures above 500°C may be possible, but issues of thermal stability will pose significant challenges. For more information, contact David S. Grummon, Michigan State University, Department of Chemical Engineering and Materials Science, 3525 Engineering Building, East Lansing, MI 48824; (517) 353-4688; e-mail grummon@egr.msu.edu.     

Ultrapure materials for alpha particle-sensitive applications

Materials used in applications where alpha particle radiation can produce “soft” or transitory errors are commonly specified and characterized in terms of uranium and thorium content, often by glow discharge mass spectrographic analysis. Analytical results indicate that low levels of uranium and thorium do not adequately reflect the alpha flux potential of some materials, especially in cases where radioactive isotopes are not in equilibrium or where a dominant decay parent other than uranium or thorium is present. An additional characterization technique—highly sensitive, surface alpha particle flux measurement—has been developed. Alpha particle counting, when used in conjunction with trace metal analysis, allows more optimum selection of low-alpha-radiation materials.     

Joining ODS materials for high-temperature applications

Oxide-dispersion-strengthened (ODS) high-temperature alloys represent a unique class of powder-metallurgy-based engineering materials. They offer combinations of high-temperature strength, oxidation resistance, and hot corrosion resistance that cannot be obtained in other alloys. The alloys were initially developed for the aircraft gas turbine industry; since then, however, applications have expanded to include industrial gas turbines, equipment for handling molten glass, high-temperature furnace assemblies, and a variety of other industrial components. Internationally, the materials are also of interest for nuclear power systems (both breeder and fusion reactors) since ferritic ODS alloys exhibit both excellent swelling resistance and good elevated-temperature creep resistance. Many of these applications require that the ODS alloys be joined to either themselves or to other materials. The purpose of this paper is to review some of the techniques available for making these joints.     

Biomedical applications of polyurethane materials and coatings

Polyurethanes (PUs), formed by the reaction of diisocyanates with polyols (or equivalent) in the presence of a catalyst, have a wide variety of industrial uses. Much recent attention has focused on their biomedical applications, owing to their biocompatibility, biodegradability and tailorable chemical and physical forms. Examples of such application areas include antibacterial surfaces and catheters, drug delivery vehicles, stents, surgical dressings/pressure sensitive adhesives, tissue engineering scaffolds and electrospinning, nerve generation, cardiac patches and PU coatings for breast implants. Following a brief introduction to PUs, this review surveys selected articles, mostly from 2014 to 2017, that highlight this diverse range of biomedical applications offered by PU materials and coatings.     

Magneto-thermo-mechanical characterization of giant magnetostrictive materials

The variations of magnetization and magnetostriction with temperature and stress were investigated through the analysis of the effective field,induced by temperature and stress.A nonlinear magnetostrictive model of giant magnetostrictive materials was proposed.The proposed model can be used to calculate the magnetostrictive characterization of giant magnetostrictive materials in different temperatures and under different stresses.The coupling effects of axial stress,magnetic field,and temperature on the magnetostriction of a Terfenol-D rod were numerically simulated as well as experimentally tested.Comparison between the calculating and experimental results shows that the proposed model can better describe the magneto-thermo-mechanical characteristics of Terfenol-D rod under different temperatures and compressive stress.Therefore,the proposed model possesses an important significance for the design of magnetostrictive devices.     

Wavelet-based AE characterization of composite materials

This paper addresses an application of recently developed wavelet-based signal processing technique on a composite fracture behavior study. Here, the wavelet methodology is introduced, and a complete procedure of wavelet-based acoustic emission (AE) analysis methods developed by the author are demonstrated. In this research, the AE signals from glass fiber reinforced (GFR) composites are collected during the standard quasi-static tensile testing and transformed by the Daubechies discrete wavelets using the programs developed by the author. Based on AE tests, the fracture behaviors are studied for the material. In the study of GFR composite fracture behavior, classical linear fracture mechanics method is used for comparison. The exponential constant m value used to determine the relationship between stress and stress intensity factor are compared relative to the classical fracture mechanics and the AE techniques. In order to demonstrate the advantage of the wavelet-based AE techniques, the conventional AE analysis is also provided side-by-side for comparison. The results verify that the wavelet-based method better approximates residual strength relative to the classical AE techniques.In this paper, the results of the wavelet-based AE analysis of glass fiber composites are presented. The results indicate that wavelets-based signal processing is an efficient tool in the analysis and the transformation of AE signals.     

Microstructural characterization of SPD processed materials

The results of a detailed microstructural characterization of bulk SPD processed nanostructured materials, and their interpretations obtained by application of the modem techniques of structural analysis are presented. It is shown that the application of advanced X-ray methods as well as TEM investigations results in evaluation of rather comprehensive information on the microstructure of SPD materials. This information includes values of the crystal lattice parameter, coherently scattering domain size, elastic microdistortions, atomic displacements, crystallographic texture, etc.