Advanced materials in golf clubs: The titanium phenomenon

Titanium golf club woods are capturing a huge share of the market for golfing equipment. This article describes this phenomenon and discusses emerging titanium irons and putters.     

Shape-memory effect in Co-Ni single crystal

The thermal shape-memory effect at room temperature for Co-32% Ni(mass fraction) magnetic shape memory alloy of single crystal was presented. When compressing the sample along the [001] direction at room temperature, strain can be recovered to some extent during later heating and the recovery rate varies with the pre-strain.But no obvious recoverable strain can be obtained along other crystal directions. For the thermal-mechanical training of the sample along [001], the recovery strain decreases obviously during the second round of compress and nearly no recovery happens after the third round of compress. A possible mechanism based on reversible motions of Shockley partial dislocations was proposed.     

Advanced synthesis of nanostructured materials for environmental applications

The present study deals with Aerosol Spray Pyrolysis (ASP) synthesis of two families of nanostructured redox materials targeted to two different environmental applications: transition-metal-doped ferrites and base metal-doped cerium oxide, used for hydrogen production through solar-assisted water splitting and for catalytic soot oxidation, respectively. The synthesized powders were characterized with respect to their phase composition, morphology and particle size distribution by XRD, SEM and TEM analysis, which have shown their nanostructured character. Doped ferrites were evaluated, with respect to their hydrogen production activity from water dissociation, in an in-house built water-splitting testing rig. ASP materials proved to be very active water splitters demonstrating higher water conversion and hydrogen yields than materials of the same composition synthesized through Solid State Synthesis (SSS), with material performance depending on the dopants’ kind and stoichiometry. Base metal-doped cerium oxides were evaluated with respect to their direct soot oxidation activity, via Thermogravimetric Analysis (TGA), as well as on a diesel engine bench under realistic conditions. It was found that doping improves their activity and that they enhance soot oxidation at lower temperatures compared to materials synthesized through Liquid Phase Self-propagating High temperature Synthesis (LPSHS).     

Shape-memory NiTi foams produced by solid-state replication with NaF

A martensitic NiTi foam was produced by hot isostatic pressing a blend of NiTi and NaF powders and subsequent dissolution of the NaF phase. The NiTi foam consists of 40 vol.% near-fully open pores, 240 μm in size, and with ragged surfaces due to incomplete NiTi powder densification. Near linear stress–strain curves are measured in compression with an average loading stiffness of 4 GPa, well below the unloading stiffness of 13 GPa because of detwinning on loading. Shape-memory recovery after unloading corresponds to 85–89% of the unloading plastic strain. After sintering at 1250 °C, the foam exhibits 20% porosity, smaller, smoother and partially-closed pores, and a shift in composition towards a martensite/austenite mixture at ambient temperature. This new composition allows for the activation of the superelastic effect in the austenite during loading and unloading resulting in average stiffnesses of 6–12 GPa, and the shape-memory effect in the martensite with 60–97% of the plastic strain recoverable.     

Advanced materials technologies of interest to the process industries

Interdependence between materials technologies and process industries is a common feature. Significant advances in science and technology are continually leading to the conception and design of new materials. An overview of some specialty materials (ceramics, polymers and composites) is provided. A summary of advances made in the metals industries (chemistry change, processing, fabrication, powder metallurgy and surfacing/coating) is presented. Multitude of innovative approaches to high performance alloys are illustrated by examples of an advanced corrosion-resistant alloy, a cobalt-free, heat-resistant alloy and a family of new wear-resistant stainless steels. Also, advances in information technology and materials expert systems are briefly outlined.     

Advanced testing methods for studying the mechanical behavior of materials

This article considers some problems associated with the selection of metallic materials used in engineering structures and environments. A common dilemma in engineering is the proliferation of newly designed (mostly high-strength and/or corrosion-resistant) steels and alloys that are unusable in industry as they are highly susceptible to failure under operating conditions including environmentally assisted cracking. The problem of materials failure has several sources, the most significant of which is how engineers select which material to use in which industry. For more information, contact S.A. Shipilov, University of Calgary, Department of Mechanical and Manufacturing Engineering, 2500 University Drive N.W., Calgary, Alberta T2N 1N4, Canada; (403) 220-4149; fax (403) 282-8406; e-mail shipilov@enme.ucalgary.ca.     

Shape-memory behaviors in an aged Ni-rich TiNiHf high temperature shape-memory alloy

The shape-memory behaviors including both one-way and two-way shape-memory effects were investigated in a Ni-rich Ti_29.4Ni_50.6Hf₂₀ alloy aged at 823 K for different hours. The precipitation of (Ti,Hf)₃Ni₄ particles strengthens the matrix strongly after the proper aging process, which should be responsible for the improvement of the shape-memory properties. Both one-way and two-way shape-memory strain increase rapidly with prolonging the aging time at the beginning of aging and then decrease with further increasing the aging time. The precipitates strengthen the matrix so that dislocations are hard to be introduced during the thermal cycling, resulting in the increase of the stability of the two-way shape-memory effect in the aged Ni-rich TiNiHf alloy. Therefore, it is feasible to use Ni-rich TiNiHf alloy as high temperature shape-memory alloy (SMA) through aging because the phase transformation temperatures are increased greatly to a high level and the shape-memory properties are also improved.     

Architectured materials: Expanding materials space

The objective of this introduction to the viewpoint set on architectured materials is to illustrate the paradigm shift which occurs by introducing additional length scales into a material in addition to those provided by the microstructure. This provides new opportunities both to relate the processing of materials directly to design needs and to develop a variety of multifunctional materials in which both the microstructure and the overall architecture of the material are optimized.     

Advanced Mg‐Mn‐Ca sacrificial anode materials for cathodic protection

Addition of calcium to the Mg‐Mn sacrificial anodes enhanced the anode efficiency by promoting the uniformly distributed corrosion along the grain boundaries and increased the driving potential by intrinsic electronegative potential of α‐Mg. The reason for the uniform intergranular corrosion is that Mg₂Ca precipitate (cathode) at grain boundaries is galvanically coupled to α‐Mg matrix (anode). Larger anodic area limits the localized nature of the intergranular attack.     

Advanced high-velocity oxygen-fuel coating and candidate materials for protecting LP steam turbine blades against droplet erosion

This paper describes the water droplet erosion characteristics of advanced high-velocity oxygen-fuel (HVOF) coating and the materials used for steam turbine blading. For droplet erosion study, round samples as per ASTM G73-98 (“Standard Practice for Liquid Impingement Erosion Testing,” Vol 03.02, Annual Book of ASTM Standards, ASTM, 2004) were selected. The materials commonly used for steam turbine blading are X20Cr13, X10CrNiMoV122, and Ti6Al4V. During incubation as well as in the long run, advanced HVOF coating has performed much better than all these materials. This is due to enhanced particle kinetic energy caused by optimum flow of oxygen and fuel injection by modifying the fuel injector. Droplet erosion test results of these materials and advanced HVOF coating along with their properties and damage mechanism are reported and discussed in this paper.     

Rotary blanking: tool materials

The growing globalization leads to an increasing demand on competition between industrial companies. The manufacturing processes using innovative operations and advanced materials make it possible to develop a competitive power with a high level productivity. In this paper the process of rotary blanking is introduced as an innovative manufacturing method. It enables users to work more efficient and to reduce product costs with a high process speed. In order to understand this modern manufacturing technology, it is needed to analyze process parameters. In particular it is necessary to determine which materials are preferable for the rotary blanking. Therefore, the influence of different tool materials on the part quality was investigated through experiments. Experimental results of the rotary blanking from different tool materials are discussed and they are compared with the results of finite element simulations in this paper.     

孔隙尺寸对Ti-7.5Nb-4Mo-2.5Sn形状记忆多孔合金超弹性能的影响

研究了孔隙尺寸对Ti-7.5Nb-4Mo-2.5Sn形状记忆多孔合金微观组织、力学性能及超弹性能的影响。结果表明,不同孔隙尺寸的Ti-7.5Nb-4Mo-2.5Sn多孔合金均由大部分β相组成,并含有少量α和α"马氏体相。随着造孔剂尺寸的增大,多孔合金孔隙尺寸逐渐增大。孔隙尺寸的增加使合金的弹性模量、屈服强度和压缩强度逐渐下降。不同孔隙尺寸的Ti-7.5Nb-4Mo-2.5Sn多孔合金均具备超弹性能,但孔隙尺寸的增加会使合金超弹性能下降。     

Processing nanostructured materials: An overview

This article reviews a variety of processing techniques for preparing nanostructured materials. A bulk nanostructured material can be produced in two-step processes by preparing nanostructured powders with subsequent consolidation, or directly in one-step processes such as electrodeposition and crystallization of amorphous solids. Principles, characteristics, and potential of both one-step and two-step processes are discussed in this paper. Although those processes have been used to produce full-density samples with little or no grain growth, further improvements are required in order to produce parts large enough for most engineering applications. Leon L. Shaw, University of Connecticut, Department of Metallurgy and Materials Engineering, Storrs, CT 06269; (860) 486-2592; fax (860) 486-4745; e-mail Ishaw@mail.ims.uconn.edu.     

Integrated computational materials engineering: A new paradigm for the global materials profession

Conclusion Integrated computational materials engineering is a field of study whose time has come. It promises to link manufacturing and design via advanced materials models in a seamless, integrated computational environment. The feasibility of ICME and its benefits have been demonstrated by several projects that have developed methods which are in use in the aerospace and automotive industries. To fully realize the potential of ICME, anumber of technical, cultural, and organizational challenges have been identified and must be overcome.