Temperature behaviour of Young's moduli of forty engineering alloys

Young's modulus and temperature data are collected graphically and tabulated for forty alloys that have technological applications. Alloy base metals include: aluminium, copper, iron, and nickel. Sources of data are: handbooks, original research at NBS, and the scientific-engineering literature. The temperature range 0 to 590 K is covered.     

A novel biomedical titanium alloy with high antibacterial property and low elastic modulus

β-type titanium alloys have attracted much attention as implant materials because of their low elastic modulus and high strength,which is closer to human bones and can avoid the problem of stress fielding and extend the lifetime of prosthetics.However,other issues,such as the infection or inflammation postimplantation,still trouble the titanium alloy's clinical application.In this paper,we developed a novel near β-titanium alloy (Ti-13Nb-13Zr-13Ag,TNZA) with low elastic modulus and strong antibacterial ability by the addition of Ag element followed by proper microstructure controlling,which could reduce the stress shielding and bacterial infections simultaneously.The microstructure,mechanical properties,corrosion resistance,antibacterial properties and cell toxicity were studied using SEM,electrochemical testing,mechanical test and cell tests.The results have demonstrated that TNZA alloy exhibited an elastic modulus of 75-87 GPa and a strong antibacterial ability (up to 98 ％ reduction) and good biocompatibility.Moreover,it was also shown that this alloy's corrosion resistance was better than that of Ti-13Nb-13Zr.All the results suggested that Ti-13Nb-13Zr-13Ag might be a competitive biomedical titanium alloy.     

Fractures in tensile deformation of biomedical Co-Cr-Mo-N alloys

Fracture behavior of Co-Cr-Mo-N alloys during tensile deformation was examined by electron backscattering diffraction. Cracks occurred at the triple junction, which consists of two grain boundaries and one annealing twin boundary. The cracks were propagated along the annealing twin boundaries and the interface between the γ-fcc phase and the ε-hcp martensite phase.     

医用钛合金的发展及研究现状

纯钛及其合金以其与骨相近似性的弹性模量、良好的生物相容性及在生物环境下优良的抗腐蚀性等在临床上得到了越来越广泛的应用；综述了医用钛合金的发展和研究现状，阐述了钛的生物相容性原理，同时简单评述了钛及其合金表面改性与钛基复合材料的研究现状，分析表明：纯钛及其合金具有出色的生物相容性主要归功于表面附着的氧化层；β型钛合金与α/α β型钛合金相比，具有较高的耐磨性，是一种很有前途的外科植入用钛合金；寻求更为理想的表面改性工艺从而获得高质量的涂层，或将生物活性相添加进钛合金基体中制备成复合材料是提高医用钛合金生物活性的两种有效途径。     

In situ studies of nonlinear d-spacing changes in titanium and steel alloys

We traced element-partitioning behavior by measuring d-spacing changes in situ during phase transformations of titanium and steel alloys using a hybrid in situ observation system. For titanium alloy, nonlinear changes are clearly evident during heating and cooling and are related to element partitioning and microstructural evolution. For low-carbon-low-alloy steel, nonlinear changes are evident during cooling and are related to bainite and carbon-enriched austenite formation.     

Effect of titanium on the ductilization of Fe-B alloys with high boron content

Binary Fe-B alloys with a high boron concentration are hard but brittle. The brittleness is caused by the formation of a cast microstructure which consists of a continuous network of brittle Fe₂B. In the present investigation, we demonstrated that, by alloying with titanium, and particularly with a titanium-to-boron atom ratio of 0.5, a fine and uniform microstructure can be formed. Also, as a result of the microstructural modification, the alloy is improved from being completely brittle (∼ zero elongation) in the Ti-free alloy to a 4% tensile elongation. The preliminary result indicates that additional rolling at 1223 K further enhances the ductility to over 16%.     

Improving the strength and biocompatibility of porous titanium scaffolds by creating elongated pores coated with a bioactive, nanoporous TiO2 layer

This paper reports a novel way of improving the mechanical properties and biocompatibility of porous Ti scaffolds using a combination of the modified sponge replication method and anodization process. The use of a stretched polymeric sponge as a novel template allowed the creation of elongated pores in a porous Ti scaffold, which, accordingly, led to a high compressive strength of 24.2 ± 2.08 MPa at a porosity of approximately 70 vol%. Furthermore, the surfaces of the Ti walls were coated successfully with a bioactive nanoporous TiO₂ layer using the anodization process, which enhanced the biocompatibility remarkably, as assessed by the attachment of MC3T3-E1 cells.     

Designation and development of biomedical Ti alloys with finer biomechanical compatibility in long-term surgical implants

Developing the new titanium alloys with excellent biomechanical compatibility has been an important research direction of surgical implants materials. Present paper summarizes the international researches and developments of biomedical titanium alloys. Aiming at increasing the biomechanical compatibility, it also introduces the exploration and improvement of alloy designing, mechanical processing, microstructure and phase transformation, and finally outlines the directions for scientific research on the biomedical titanium alloys in the future.     

Anisotropy of Young's modulus and tensile properties in cold rolled α′ martensite Ti–V–Sn alloys

Young's modulus and tensile properties of cold rolled Ti–8 mass% V and (Ti–8 mass% V)–4 mass% Sn alloy plates consisting of α′ martensite were investigated as a function of tensile axis orientation in this work. A single phase of α′ (hcp) martensite is obtained in Ti–8 mass% V and (Ti–8 mass% V)–4 mass% Sn alloys by quenching after solution treatment. By 86% cold rolling, acicular α′ martensite microstructures change into extremely refined dislocation cell-like structure with an average size of 60 nm, accompanied with the development of cold rolling texture in which the basal plane normal is tilted from the plate normal direction (ND) toward transverse direction (TD) at angles of ±49° for Ti–8% V alloy and ±46° for (Ti–8 mass% V)–4 mass% Sn alloy. No apparent anisotropy of Young's modulus (E) is observed for as-quenched Ti–8% V (E = 76–83 GPa) and (Ti–8% V)-4%Sn (E = 69–79 GPa). In contrast, Young's modulus increases with increasing angle from the rolling direction (RD) to TD for cold rolled Ti–8% V (E = 72–94 GPa) and (Ti–8% V)–4%Sn (E = 63–85 GPa). The observed anisotropy of Young's modulus can be reasonably explained in terms of the cold rolling α′ texture.0.2% proof stress and tensile strength are independent of tensile orientation for cold rolled Ti–8% V and (Ti–8% V)–4%Sn alloys. In contrast, larger elongation to fracture is obtained in specimens deviated by 30°, 45° and 60° from RD than by 0°, 75° and 90°. Scanning electron microscopy (SEM) fractographs reveal that quasi-cleavage-like fracture plane appears in 0° specimen of cold rolled Ti–8% V which shows brittle fracture and other specimens of cold rolled Ti–8% V and (Ti–8% V)–4%Sn alloys are fractured accompanied with necking and dimple formation. It is suggested from these results that brittle fracture is related to the activation of limited number of slip system and Sn addition leads to the activation of multiple slip systems.     

选区激光熔化3D打印钛合金及其复合材料研究进展

选区激光熔化(SLM)3D打印技术作为近年来快速兴起的增材制造技术,在航空航天、国防和生物医疗用高性能钛合金及其复合材料关键及复杂结构件方面具有显著优势、发展潜力巨大.SLM 3D钛合金晶粒细小且常含有大量的α′马氏体,而SLM 3D钛基复合材料中则通常可以原位生成纳米尺度的TiBw和TiCp等陶瓷增强相,使得成形构件的力学性能显著优于铸件和粉末冶金制品水平.本文在介绍SLM 3D打印技术的原理与特点基础上,着重评述了其在钛合金及其复合材料的应用基础研究及工程应用进展,并对未来相关关键基础科学与技术问题进行了展望.     

Nanoindentation of Ni-Ti Thin Films

Ni-Ti thin films of various compositions were sputtered-deposited on silicon substrates. Their mechanical properties (hardness and Young's modulus) were then determined using a nanoindenter equipped with a Berkovich tip. This paper examines the effects of composition on the mechanical properties (hardness and Young's modulus) of the sputter deposited Ni-Ti thin films. This is of particular interest since the actuation properties of these shape memory alloy films are compositionally sensitive. The surface-induced deformation is revealed via Atomic Force Microscopy (AFM) images of the indented surfaces. Which show evidence of material pile-up that increases with increasing load. The measured Young's moduli are also shown to provide qualitative measures of the extent of stress-induced phase transformation in small volumes of Ni-Ti films.     

Potentiodynamic behaviour of Ti alloys in physiological solution containing lubricant

Ti based alloys are finding wide spread usage in various biomedical applications including joint replacement. The corrosion behaviour of these alloys in simulated body fluid conditions in the presence of lubricant is not reported so far. Thus, present work is undertaken to understand the influence of the lubricant on potentiodynamic behaviour of three types of Ti alloy, namely commercially pure (C.P.) Ti having α structure, Ti-6Al-4Fe having α + β structure and Ti-13Ta-29Nb-4.6Zr having β structure in Ringer's solution. The results show that lubrication does not alter the corrosion rates of single-phase alloys, which have low corrosion rates. However, it significantly reduces the corrosion rates of alloy Ti-6Al-4Fe having α + ß structure.     

组合材料芯片技术在钛合金研究中的应用

综述了组合材料芯片技术在钛合金研究中应用的新进展.利用组合材料芯片技术在短周期内制备出合金元素梯度变化的多元钛合金样品,由于样品的加工状态和热处理条件相同,可以确定某种合金元素含量与整个钛合金体系组织和力学性能的定量关系.利用多种表征手段,从样品库中系统地分析组织和力学性能的变化规律并筛选出目标成分,显示出组合材料芯片技术在钛合金相变研究和合金设计中的优势.     

Effect of magnetic field on interfacial energy and precipitation behavior of carbides in reduced activation steels

This work investigated the influence of high temperature and high magnetic field on the carbide precipitation behavior in reduced activation steels. As-quenched steels are tempered at 923 K for 3 h with and without a 10 T magnetic field. The applied field can effectively prevent the directional growth of rod-shaped M₂₃C₆ carbides along martensite packet boundaries. The aspect ratio of M₂₃C₆ carbides decreased from 2.3 to 1.2 due to an increase of the carbide/ferrite interfacial energy under the high magnetic field. Applications of the Weiss molecular field theory to calculate the difference in interfacial energy caused by the high magnetic field, and of the Langer-Schwartz theory to model metal carbide (MC) precipitation behavior under the magnetic field were described. Results indicated that the density of MC decreased by nearly an order of magnitude and its mean size increased by 40% owing to an increase of 0.03 J/m² of the carbide/ferrite interfacial energy.     

Formation of reactive layers in brazed Ti and Cu using a melt-spun Zr41.2Ti13.8Ni10.0Cu12.5Be22.5 alloy

Investigations on the microstructure of brazed Ti and Cu when using a Zr_41.2Ti_13.8Ni_10.0Cu_12.5Be_22.5 alloy revealed that mainly Ti-rich compounds were formed at the brazed joint after brazing at 790 °C for 10 min. However, detailed microstructural investigations revealed that the interfacial areas close to the Cu consisted of orthorhombic Cu₄Ti, orthorhombic Cu₃Ti, hexagonal Cu₂TiZr and tetragonal CuTi compounds. The formation of a Cu₂TiZr Laves phase at the interfacial areas close to the Cu possibly suppresses a diffusion of Cu into the central areas of the brazed joint due to its characteristics of a high solubility and high melting temperature.     

Calculating the fatigue life of smooth specimens of two-phase titanium alloys subject to symmetric uniaxial cyclic load of constant amplitude

A system of microstructure-dependent fatigue failure models that allows calculating the number of stress cycles to failure of smooth specimens in the absence of data on the fatigue resistance of the material is proposed. Fatigue life is represented as the sum of the number of stress cycles to the initiation of a microstructurally short crack with a depth equal to one grain size and the number of stress cycles to the instant the growing physically small and long crack reaches the depth taken as a fatigue failure criterion. To fill the models, it is necessary to test standard specimens under monotonic short-term tension to determine the elastic modulus, Poisson’s ratio, and the proportional limit and to analyze the microstructure and texture of the material to determine the Taylor factor, the magnitude of the Burgers vector, and the distance between neighboring parallel slip planes in the lattice, depending on which slip system is activated relative to the tension direction. The models are applicable to metals and alloys in which a fatigue crack is initiated along a persistent slip band in a surface grain under high-cycle loading. The models are validated against fatigue test data for flat specimens of different two-phase titanium alloys (VT3-1, IMI 834, Ti–6Al–4V, VT6, VT16, VT22, VT23, LCB) with different types of microstructure (bimodal, globular, fine-grained β-transformed) subject to symmetric in-plane bending. The plotted S–N curves are in a satisfactory agreement with experimental data.     

Formation of face-centered cubic titanium in laser surface re-melted commercially pure titanium plate

Micron-scale face-centered cubic titanium phase(named as δ phase) were noticed in the re-melted zone of laser surface re-melted commercially pure titanium plate.The morphology,sub-structure,orientation and distribution of δ phase were investigated by scanning electron microscopy,electron back-scattered diffraction and transmission electron microscopy.Three kind formation processes of δ phase were put forward based on the investigation.The first one is α'→δ transformation which takes place in single α'grains and leads to the orientation relationship {001}δ//{0001}α' 110 δ// 1120 α'.The second one is β→α'+ δ transformation which takes place at α'/α'interfaces and leads to the orientation relationship{001}δ//110β110 δ//111β.The third one is another kind of β→α'+ δ transformation that takes place at α'/α'interfaces and leads to the orientation relationship111δ//110β 110 δ// 111 β.It is believed that the transformations of δ phase are stress assistant ones and in the present investigation,the phase transformation stress of β→α'transformation acts as the assistant driving force for the formation of δ phase.     

Exudation of Ag and Cu in internally oxidized Ag-Sn-In-(Cu) alloys

Growth and structure of pure Ag layers are investigated on the surface and at grain boundaries of Ag alloys that have been internally oxidized. Two Ag-Sn-In and an Ag-Sn-In-Cu alloy were studied by ion polishing, field emission scanning electron microscopy and optical microscopy. As already known from previous studies Ag atoms diffuse towards the surface. In the present study it is shown that grain boundaries can act as a sink for diffusing Ag atoms in competition with the surface. In the quaternary alloy Ag and Cu diffuse towards the surface simultaneously. The Cu diffusion is confined by the nucleation of CuO particles. The progress of the internal oxidation front is discussed in conjunction with the nucleation of pure Ag crystallites and CuO particles at grain boundaries.     

Structure, magnetic and magnetostrictive properties of Sm0.7Pr0.3Fex alloys

The structure, magnetic and magnetostrictive properties of Sm_0.7Pr_0.3Fe_x (1.45 ≤ x ≤ 1.95) alloys is investigated. X-ray diffraction analysis confirms the presence of single cubic Laves phase in Sm_0.7Pr_0.3Fe_x alloys with 1.45 ≤ x ≤ 1.85. The saturation magnetization of the alloys tends to increase with increasing Fe content. Sm_0.7Pr_0.3Fe_1.55 has the highest magnetostriction among all the Sm_0.7Pr_0.3Fe_x alloys at low fields and shows a large magnetostriction λ_// − λ_⊥ = −1008 ppm at a magnetic field of 12 kOe.     

Precipitation kinetics of the hardening phase in two 6061 aluminium alloys

The purpose of this work is to study the kinetics of the precipitation of the hardening phase in two Al-Mg-Si alloys. A review of the theoretical framework for solid-state reaction kinetics and the determination of kinetic parameters from DSC curves are provided, then used to quantify β″ precipitation in the two alloys studied. Despite failure to achieve high levels of accuracy, due, in particular, to the dilution of the alloys, the procedure to analyse this precipitation reaction yields valuable results. It is established that β″ precipitates homogenously as needles which grow through an enhanced-diffusion mechanism.