G.P.Li
,
D.Li
,
Y.Y.Liu
,
S.X. Guan and Q.J.Wang (Department of Titanium Alloys
,
Institute of Metal Research
,
The Chinese Academy of Sciences
,
Shenyang 110015
,
China)
金属学报(英文版)
TEM examination proves that the second phase particle within the as-forged Ti-55alloy consists of either bright or dark "matrix" (nano-Nd3Sn) and some small dark blocks (SnO) dispersed in the "matrix". The HREM observation shows that the nanoNd3Sn phase is roughly spherical and about 3-15nm in diameter, and the grain boundaries with atout 1nm width are "gas-like" structure.
关键词:
Ti alloy
,
null
,
null
Journal of Applied Physics
Influence of alloying elements M (M=Al, Cr, Cu, Fe, Mo, Nb, Ni, Sn, Ta, V, W, and Zr) on phase stability and elastic properties of titanium was studied by first principles total energy calculations. The formation energies of various phases of binary Ti-M alloys are evaluated to identify the influence of alloying elements on phase stability and transformation. The results show a similar dependency of the formation energy on the concentration of alloying elements in various phases: the beta, alpha', alpha '', and omega phases. All alloying elements stabilize the beta phase and show similar influence of the stabilities of the alpha' and alpha '' phases, but only Al and Sn can increase the stability of the omega phase. The elastic parameters of alpha ''-Ti alloys are also studied in the present work. All alloys have smaller Young's modulus than the pure titanium except the Al and Cu contained alloys, which also show larger bulk and shear moduli than the pure Ti. Elements Cr, Mo, Ni, Sn, Zr, Al, and Cu could stabilize the alloys both energetically and mechanically. Sn and Cr cause the elastic anisotropies, while Zr and Al greatly increase the isotropic properties. The electronic structures are evaluated to study the intrinsic mechanisms of how alloying elements influence the phase stability and transformation and elastic properties of titanium. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4770481]
关键词:
shape-memory alloys;ti-mo alloys;elastic-constants;gum metal;deformation;microstructure;superelasticity;elements;ti-10v-2fe-3al;behavior
LIU Ping Institute of Aeronautical Material
,
Beijing
,
ChinaXU Changgan Beijing University of Aeronautics and Astronautics
,
Beijing
,
China XU Changgan
,
Associate Professor
,
Group 102
,
Beijing University of Aeronautics and Astronautics
,
37 Xueyuan Road
,
Beijing 100083
,
China
金属学报(英文版)
The electrochemical behaviour,which is presented by means of anodic polarization curves.of the component phases in Ti and Ti alloys in aqueous solutions of fluorhydrie acid,chhnhydric acid and amber acid has been investigated.The results indicate that the electrochemical behaviour of the allloys depends upon the composition and the lattice type.The corrosion of x and x′phase in actire region and that of β phase in passive region are the dominant corrosion behaviour.
关键词:
Ti alloy
,
null
,
null
Materials Science and Engineering a-Structural Materials Properties Microstructure and Processing
Titanium alloys are favorable implant materials for orthopedic applications, due to their desirable mechanical properties and biochemical compatibility (or bio-inertness). However, current bio-titanium alloys still possess too high an elastic modulus compared with that of the bone, which can lead to premature failure of the implant. Here, a theoretical methodology for the design and development of low modulus Ti alloys and/or structures is provided by means of electronic structural calculations using the discrete variational cluster method (DVM). The preliminary study concentrated on two beta-Ti atomic clusters consisting of 15, and 27 atoms, respectively. The binding energies between titanium and various alloying atoms within the clusters were first calculated, from which strength and modulus were then estimated. The results of the calculation suggested that Nb, Mo, Zr and Ta were suitable alloying elements for beta-type titanium alloys, capable of enhancing the strength and reducing the modulus of the materials. (C) 1999 Elsevier Science S.A. All rights reserved.
关键词:
electronic simulation;alloy design;titanium;strength;modulus;biomaterial;site occupancy
Physical Review Letters
We report a ductile beta-type titanium alloy with body-centered cubic (bcc) crystal structure having a low Poisson's ratio of 0.14. The almost identical ultralow bulk and shear moduli of similar to 24 GPa combined with an ultrahigh strength of similar to 0.9 GPa contribute to easy crystal distortion due to much-weakened chemical bonding of atoms in the crystal, leading to significant elastic softening in tension and elastic hardening in compression. The peculiar elastic and plastic deformation behaviors of the alloy are interpreted as a result of approaching the elastic limit of the bcc crystal under applied stress.
关键词:
plastic-deformation;gum metal;shear;behavior;solids;iron
Physical Review B
Titanium alloys exhibit three distinct crystal structures: alpha, beta, and omega. For various applications alloying elements can be used to stabilize the desired phase. Extensive data exist to determine the thermodynamic equilibrium phase, typically phase coexistence. However, the normal state of commercial alloys is a quenched solid solution. While alloy designers have well-established rules of thumb, rigorous theory for nonequilibrium single-phase crystal stability is less well established. We develop a theory to predict which phase a particular alloy will adopt, as a function of minor element concentration. We use two different methods based on density functional theory with pseudopotentials and plane waves, with either explicit atoms or the virtual crystal approximation (VCA). The former is highly reliable, while the latter makes a number of drastic assumptions that typically lead to poor results. Surprisingly, the agreement between the methods is good, showing that the approximations in the VCA are not important in determining the phase stability and elastic properties. This allows us to generalize, showing that the single-phase stability can be related linearly to the number of d electrons, independent of the actual alloying elements or details of their atomistic-level arrangement. This leads to a quantitative measure of beta stabilization for each alloying transition metal.
关键词:
crystal-structures;structure maps;approximation;metals;zr;ti;hf
Yong LIU
,
Lifang CHEN
,
Weifeng WEI
,
Huiping TANG
,
Bin LIU
材料科学技术（英文）
Ti-4.5Al-6.0Mo-1.5Fe, Ti-6Al-1Mo-1Fe and Ti-6Al-4V alloys were prepared by blended elemental powder metallurgy (PM) process, and the effects of Nd on the microstructures and mechanical properties were investigated by scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray diffraction (XRD). It was found out that the addition of Nd increased the density of sintered titanium alloys slightly by a maximum increment of 1% because small amount of liquid phase occurred during sintering. The addition of Nd shows little effect on the improvement of tensile strength, while the elongation is significantly improved. For example, the elongation of Ti-4.5Al-6.0Mo-1.5Fe can be increased from 1% without addition of Nd to 13% at a Nd content of 1.2 wt pct.
关键词:
Powder metallurgy titanium alloy
,
null
,
null
,
null
鲁二敬
,
卢峰华
,
许鸿吉
,
谢明
,
钮旭晶
机械工程材料
通过周期浸润腐蚀试验，对比研究了S355．12W耐候钢和Q345R低合金钢在NariSOs溶液中的耐腐蚀性能，并用扫描电镜对腐蚀产物进行了观察和分析。结果表明：在相同试验条件下，S355J2W耐候钢的腐蚀速率低于Q345R钢的；S355J2W耐候钢会在表面形成黑褐色锈层，而Q345R钢表面形成橘红色易剥落的疏松锈层；S355J2W耐候钢腐蚀产物微观形貌为沿放射性方向生长的针状晶体，Q345R钢为颗粒状聚合物堆积而成，形状无规则，颗粒之间有较大的空隙。
关键词:
S355J2W耐候钢
,
周期浸润腐蚀试验
,
耐腐蚀性能
