Ti3Zr2Sn3Mo25Nb钛合金表面细晶的表征方法

采用超声冲击的方法对Ti3Zr2Sn3Mo25Nb钛合金进行表面强化，采用扫描电镜、透射电镜、电子背散射衍射仪、X射线衍射仪等设备对其表面细晶进行表征。结果表明：超声冲击后，钛合金表面获得了深度约为35μm的强塑性变形层；钛合金表面可观察到明显纳米级的非晶团簇和密集的滑移线，细晶形成的主要原因为位错滑移，位错滑移的主方向为<111>;超声冲击后，材料的表面残余压应力约为250 MPa,晶格常数略有降低，β相的特征峰强度变大，α相的特征峰宽度变大。     

Ti－15－3钛合金的应用研究

研究了冷加工对Ｔｉ－１５－３合金时效性能的影响，并研究了该合金的冷成形性能及零件制造工艺，为Ｔｉ－１５－３高强钛合金钣金零件的应用提供了经验。     

Ti－15－3钛合金的成分控制及性能研究

研究了铝和氧对Ｔｉ－１５－３钛合金的力学性能和冷成形性能的影响，提出了该合金的成分控制范围，为该合金的工业化稳定生产提供了依据。针对我国的国情，提出了与３０ＣｒＭｎＳｉＡ结构钢等强度的时效制度，并研究了相应的力学性能。     

阳极氧化电压对β型Ti-12Mo-3Nb钛合金表面形貌和亲水性的影响

在医用钛合金表面制备TiO2纳米管阵列是提高其生物相容性的有效手段.以成本相对较低的新型β型生物钛合金Ti-12Mo-3Nb为对象,在含NH4F(0.5％)的丙三醇水溶液中,利用阳极氧化法在其表面制备TiO2基纳米管阵列,研究阳极氧化电压(20～50 V)对纳米管阵列形成过程、形貌以及亲水性的影响.结果表明,Ti-12...     

Fe60Co8Zr10Mo5W2B15块体非晶合金的形成及热处理对性能的影响研究

用铜模吸铸法获得直径为2mm的Fe60Co8Zr10Mo5W2B15和Fe60Co8Zr10Mo5W2B15块体非晶合金。采用X射线衍射（XRD）、示差扫描量热分析（DSC）、显微硬度及压缩实验等研究了非晶合金的结构、热稳定性及热处理前后的显微硬度与压缩性能。结果表明Nb的引入不利于非晶合金的形成；Fe60Co8Zr10Mo5W2B15非晶合金的显微硬度为1343HV0．2，抗压强度σbe为972．6MPa；在低于晶化起始温度的热处理，硬度稍有下降；但在高于晶化峰值温度的热处理，硬度值随时间变化先升高，后下降；在热处理时间相同的条件下，随着热处理温度的升高，合金的硬度升高，但压缩强度会明显下降。     

用第一性原理研究Ti掺杂β-Ga_2O_3的电子结构和光学性能(英文)

用GGA+U的方法研究了本征β-Ga2O3和Ti掺杂β-Ga2O3的电子结构和光学性能。晶格常数的计算值与实验值差别小于1%,本征β-Ga2O3的带隙计算值4.915eV,与实验值4.9eV一致。Ti替位Ga(1)位置和Ti替位Ga(2)位置的β-Ga2O3的价带最大值和导带最小值间隙分别为4.992eV和4.955eV,Ti掺杂引入的杂质带起到中间带作用,可以使电子从杂质带跃迁到导带和价带跃迁到杂质带。Ti掺杂β-Ga2O3中间带的存在使其成为潜在的宽光谱吸收太阳能电池材料。     

Ba0.85Ca0.15Zr0.1Ti0.9O3/CoFe2O4叠层复合陶瓷的制备与磁电耦合效应研究

以CoFe2O4压磁体、掺CuO和CeO2助烧剂的压电体Ba0.85Ca0.15Zr0.1Ti0.9O3为基本叠层材料,采用界面固相熔融渗透法制备了掺助烧剂Ba0.85Ca0.15Zr0.1Ti0.9O3-CoFe2O4叠层复合陶瓷。叠层复合陶瓷的压电压磁相叠层界面结合良好。随着压磁相与压电相厚度比比率的增加,叠层复合陶瓷的饱和磁致伸缩系数–λ从67×10-6增加到134×10-6、压电系数d33从340 pC/N逐渐减小到205 pC/N;磁电耦合系数先增大后减小,在厚度比为2、外磁场为100 mT时得到最大值3200 mV/(cm.mT)。     

Mechanical properties of Zr-3Sn-1Mo-1Nb alloy at various temperatures

The deformation characteristics of Zr-3Sn-1Mo-1Nb alloy have been investigated by tensile testing in the temperature range 300–1000 K at a constant crosshead speed corresponding to the strain rate of 6.7×10^–5s^–1. At lower temperatures, below about 500 K, the flow stress of the sample decreased with increasing temperature, whereas an inverse temperature dependence of the yield stress was found at temperatures between 500 and 700 K. At higher temperatures, above 700 K, the normal dependence of the yield stress on temperature was again observed. The maximum stress exhibited a similar temperature dependence. At higher temperature, serrations were found on the flow stress curves at the very beginning of deformation. The main deformation mechanisms are assumed to be a locking-unlocking mechanism connected with cross-slipping.     

The twisting mechanism of subsurface fatigue cracking in Ti-6Al-2Sn-4Zr-2Mo-0.1Si alloy

The initiation phenomenon of a subsurface fatigue crack was examined by monitoring of the acoustic emission (AE) effects revealed by the slightly surface-hardened specimens of titanium-based VT3-1 (Ti-6Al-2Sn-4Zr-2Mo-0.1Si) alloy under fatigue tests. The circumferentially notched round-bar specimens were cyclically stretched in the stress range of 720-680 MPa, with the stress ratio varying as 0.31-0.36, at 35-Hz loading frequency. The AE monitoring has shown the subsurface cracking events as concomitant with the unloading (compressive) portions of the cyclic load trajectory. In the several fractographically examined areas of subsurface fatigue fracture, mode III (rotational or twist-like) way of crack opening was found to dominate on the short-crack path; during the damage-accumulation period, creative of the first smooth crack-origin facets, such a crack-opening pattern appeared mainly related to the unloading portions of the loading trajectory. Internal residual stresses appear to control such a deformation mode in the locally compressed material. Stress-release effects should follow from the occurrence of the first crack facet favoured by gas diffusion. Therefore, the subsurface crack origination is actually a synergetic problem. The dominant mode-III deformation is also creative of a plastic zone around the now stress-released area of the first fracture facet. This plastic zone is to be involved in the mode-I (tension) opening of the subsurface crack propagating from the first subsurface crack facet. The subsurface crack opening occurs as facilitated by the dissolved-gas diffusion toward a material discontinuity. Consequently, a short crack can expand around the first facet through a combined modes III and I opening to form a growing subsurface-fracture area. Such a model of the twist-controlled subsurface cracking is proposed and discussed here in terms of the well-known numerical data on the subsurface stress-state evolution as well as on the progress of plastic mesoscopic-scale level deformation in tensile-loaded metals.     

Mechanism and kinetics of carbide dissolution in near alpha Ti-5.6Al-4.8Sn-2Zr-1Mo-0.35Si-0.7Nd titanium alloy

The present work evaluates the influence of bulk carbon content and aging temperature on the stability of carbide in near alpha Ti-5.6Al-4.8Sn-2Zr-1Mo-0.35Si-0.7Nd titanium alloy. The carbide particles were formed during heat treatment in the β phase field and preserved by water quenching. Subsequent aging treatments at 750–850 °C caused partial dissolution of these precipitates, as a result of the peritectoid reaction between the β phase and carbide. The models based on interface reaction controlled dissolution, via uniform atomic detachment, dislocation mechanism or vacancy flow, yielded experimental predictions comparable to the observed dissolution kinetics. Furnace cooling after heat treatment in the β phase field dissolved carbide particles completely, and the microstructure changed from acicular-like or block α to equiaxed α with increase of carbon content.     

Shape memory and superelastic behavior of Ti–7.5Nb–4Mo–1Sn alloy

In the present work, a Ti-based shape memory alloy with the composition of Ti–7.5Nb–4Mo–1Sn was designed based on the d-electron orbit theory. The shape memory and superelastic behavior of the alloy were investigated. It is found that the martensitic transformation temperature of the alloy is near 261 K. The tensile and the thermal cycling testing results show that the alloy exhibits the stable shape memory effect and superelasticity at room temperature. The maximum recovered strain of the alloy is 4.83%.     

TiCP/Ti-6Al-4Sn-2Mo-0.2Si复合材料的组织与机械性能

用熔铸法制备了体积分数分别为8%和12％TiC的TiCp/Ti-6Al-4Sn-2Mo-0.2Si复合材料，通过SEM、TEM、XRD等手段研究复合材料的微观组织和断口形貌。TiC颗粒的加入使复合材料的铸态强度比基体有了大幅度的提高，但同时出现了含低体积分数增强相材料的强度和延伸率均比高体积分数材料高的现象，其原因主要来自于铸态下TiC形态的差异，后者组织中存在较多的枝晶状TiC，而前者组织中绝大多数TiC为细小颗圆整颗粒，有利于合金性能的提高。因此自生复合材料中增强相形态对性能影响，有时比体积分数更重要。     

Microstructural Evolution of Ti-5.6Al-4.8Sn-2Zr-1Mo-0.35Si-0.7Nd Titanium Alloy with Carbon Additions

The effect of carbon addition on microstructural evolution was studied in a near-α titanium alloy(Ti-5.6Al-4.8Sn-2Zr-1Mo-0.35Si-0.7Nd). It was found that flake and ribbon titanium carbides with a NaCl crystal structure formed in the as-cast alloys with carbon additions of over 0.17 wt pct. Flake carbide particles are the product of eutectic transformation and precipitate from the high-temperature β phase. The ribbon carbide particles are primary phases formed prior to the nucleation of any metallic phases. The as-cast alloys with carbide precipitation after heat-treatment atβt-30℃ followed by water quenching showed the spheroidization of α lamellae and partial dissolution of carbide particles. After annealing at βt 15℃, carbide particles are mostly distributed at the grain boundary and spheroidized through mixed grain boundary plus bulk diffusions.     

Ti-27Mo-1.5Nb无磁不锈定膨胀合金研究

研究了一种Ti-27Mo-1.5Nb新型无磁不锈定膨胀合金,该合金的膨胀系数为7.70×10-6/℃,磁导率为1.0003,同时研究了Ti-27Mo-1.5Nb合金的微屈服强度及其它机械性能和物理性能,该合金还是良好的耐腐蚀材料,试验表明,Ti-27Mo-1.5Nb合金是诸如静电陀螺等电真空领域中与高纯Al2O3匹配的良好封接材料。     

Structure of Second Phase Particles in As-cast Ti-5Al-4Sn-2Zr-1Mo-0.25Si-1Nd Alloy

The microstructure of the Ti-5Al-4Sn-2Zr-1Mo-0.25Si-1Nd (Ti-55) alloy containing second phase particles was studied. The second phase particles are 1~15 μm in size and most of them are distributed at the grain boundaries in the form of ellipsoid with a few short needle-like and blocky phases. It consists of either dark or bright amorphous "matrix", and some small spots dispersed within the "matrix", which match SnO (orthorhombic, a=0.500 nm, b=0.572 nm, c=1.12 nin).