硅化物涂层对Nb?Ti?Al合金力学性能的影响

采用真空电弧炉熔炼法制备低密度Nb?Ti?Al合金铸锭,利用料浆烧结法在铸锭表面涂覆Si?Cr?Ti复合硅化物涂层,使用万能电子拉伸试验机对合金试样和涂层试样进行力学性能测试,研究硅化物涂层对试样力学性能的影响。结果表明,与合金试样相比,涂覆涂层后的低密度铌合金室温力学性能（抗拉强度、屈服强度及延伸率）显著下降。为进一步研究涂覆涂层合金力学性能下降的原因,采用扫描电子显微镜和能谱仪对合金试样和涂层试样进行显微组织观察、涂层/基体界面成分分析及C含量（质量分数）测定。结果表明,涂层试样力学性能下降的主要原因包括涂覆涂层后合金晶粒显著长大,合金中强化元素Al的向外扩散,脆性相Nb₃Al的形成以及Si?Cr?Ti涂层对合金产生的“渗沉效应”。     

温度对一种高固溶强化β钛合金损伤行为的影响

Ti25V15Cr0.3Si合金含有40%左右的合金元素,是一种高固溶强化的β钛合金。测试了Ti25V15Cr0.3Si合金在室温(25℃)至600℃下的裂纹扩展性能,发现随着温度升高,裂纹扩展速率增大。与Ti6Al4V和β21S合金相比,室温下Ti25V15Cr0.3Si合金的裂纹扩展速率高于Ti6Al4V而低于β21S合金。600℃高温下,Ti25V15Cr0.3Si合金的裂纹扩展速率与β21S在650℃时的水平相当。研究结果表明,合金的屈服强度、弹性模量、断裂韧性、氧化性能和组织结构特征综合影响着Ti25V15Cr0.3Si合金的裂纹扩展损伤行为。从室温到300℃,随温度的升高,Ti25V15Cr0.3Si合金的屈服强度和弹性模量降低同时断裂韧性升高,因此裂纹扩展速率变化不明显;而从500～600℃,温度升高氧化加剧,合金疲劳裂纹扩展速率明显增加。与Ti6Al4V合金相比,室温下,Ti25V15Cr0.3Si合金相对于Ti6Al4V合金具有较低的弹性模量以及等轴的β组织,裂纹扩展速率较高。而与β21S合金相比,Ti25V15Cr0.3Si合金的屈服强度和弹性模量高于β21S合金,因此裂纹扩展速率较低。6...     

辉光放电光谱法测定因瓦合金中14种元素

采用11种与因瓦合金成分含量相接近的镍基合金标准样品绘制校准曲线,建立了基本不需要样品处理即可对因瓦合金中14种元素(C、Si、Mn、P、S、Ni、Cr、Mo、Cu、Al、Nb、Ti、Co、Fe)同时测定的辉光放电光谱法。确定辉光光谱仪检测因瓦合金的最佳条件:模块电压和相电压分别为8.22 V和3.82 V;功率为70 W;冲洗时间为80 s;积分时间为60 s。以各元素质量分数为横坐标,其对应的光谱强度为纵坐标绘制校准曲线,各元素校准曲线的相关系数均在0.99以上。采用实验方法对因瓦合金实际样品进行分析,结果显示:Cr、Ni、Mo、Ti、Fe的质量分数均大于0.3%,各元素测定值的相对标准偏差(RSD,n=11)均不大于1%;C、Si、Mn、P、S、Cu、Al、Nb、Co的质量分数均小于0.3%,各元素测定值的RSD(n=11)均小于5%。将实验方法应用于对因瓦合金样品中14种元素的测定,测得结果与滴定法测定Ni和Fe、高频燃烧红外吸收法测定C和S、电感耦合等离子体原子发射光谱法测定Si、Mn、P、Cr、Mo、Cu、Al、Nb、Ti和Co元素的结果基本一致。     

以铝为助剂通过机械合金化和热处理制备Ti3SiC2

采用Ti、Si、C单质粉末为原料,添加少量Al元素粉末为助剂,通过机械合金化和热处理制备高纯Ti3SiC2材料。采用XRD和SEM研究该材料的物相组成和显微结构。研究结果表明,机械合金化Ti、Si、C单质混合粉末,会诱发自蔓延反应,生成组成相为TiC、Ti3SiC2、TiSi2和Ti5Si3的粉末与颗粒产物。添加适量的Al元素可消除硅化物,明显促进Ti3SiC2的反应合成。采用Ti、Si、C、Al单质粉末进行机械合金化,可制备出主相为TiC与Ti3SiC2的粉末与颗粒产物。对掺Al机械合金化粉末产物压制后,在900~1 100℃热处理2 h,可制备出纯度大于95%(质量分数)的Ti3SiC2材料,而颗粒产物在900~1 200℃进行热处理,亦可获得纯度为96%的Ti3SiC2材料。但在1 300℃,热处理产物中的Ti3SiC2会发生严重分解,部分分解为TiC和少量硅化物,使产物纯度降低。     

一种高热稳定性等轴纳米晶Ti6Al4V-Cr合金及其制备方法

本发明涉及钛合金材料领域,具体为一种高热稳定性等轴纳米晶Ti6Al4V-Cr合金及其制备方法。该钛合金的化学成分(质量分数,%)如下:Al 5.0～7.0,V 3.0～5.0,Cr 0.01～6.5,余量为Ti。该钛合金的制备方法如下:首先,Ti6Al4V-Cr合金在950℃以上保温一段时间后,快速冷却至室温以获得纳米板条前驱体;随后在温度为650～850℃,应变速率为0.1～5 s-1的范围内对纳米板条前驱体钛合金进行热变形,总应变量大于等于70%,使纳米板条前驱体转变为等轴纳米晶结构。本发明所制备的高热稳定性纳米晶Ti6Al4V-Cr合金具有优异的综合力学性能,可广泛应用于航空航天、生物医疗、石油化工、汽车工业和海洋工程等诸多领域。     

一种适用于增材制造的钛合金

<正>申请号:CN202110249195.3申请日:20210308公开(公告)日:20220913公开(公告)号:CN115044802A申请(专利权)人:南京理工大学摘要:本发明公开了一种适用于增材制造的钛合金，其化学成分(质量分数)为:Al 3.0%～3.5%,Fe 2.0%～2.5%,Si 0.1～0.3%,V 2.5%～3.0%,O 0.07%～0.1%,C≤0.06%,Cr≤0.03%,Cu≤0.015%,Mn≤0.03%，余量为Ti。通过精确控制得到适合于增材制造的钛合金并将其制成丝材或粉末后用于增材制造，     

用氢细化Ti—6Al—4V合金显微组织的研究

本文介绍了用氢细化Ti—6Al—4V合金显微组织的方法。利用氢在钛中的可逆性,作临时性的合金化元素,可改善铸造钛合金的粗大魏氏组织,强化力学性能,提高疲劳寿命。     

过渡金属元素在L10-TiAl中占位行为的热力学研究

从合金热力学的角度,采用一种普适化的三亚晶格热力学模型,辅助以第一性原理总能计算的方法,研究了常用于添加在L10-TiAl基金属间化合物中的12种过渡族金属元素的占位行为随Ti/Al比和温度的变化情况.结果表明,在1173 K,合金化元素含量固定为2％(原子分数),Ti/Al比从0.6增加至1.4时,Ti和Al本身具有很强的占位有序性.当温度固定为1173 K,Ti/Al比从0.6增加至1.4时,合金化元素按其占位行为可以分为两大类,其中,V,Ta,Mo,Mn,Cr,Zn和W元素随Ti/Al比的增加,其占位行为在Ti/Al=1附近出现了从占Ti位到Al位的突变;Zr,Nb,Tc,Co和Ag元素的占位行为随Ti/Al比变化没有明显变化.当Ti/Al=1,合金体系固定为Ti0.49Al0.49M0.02,温度从200 K增加至2000 K时,合金化元素按其占位行为同样可以分为两大类,其中,V,Ta,Mo,Tc,Co,Mn,Cr,Zn和W元素随温度升高,其占位行为从完全无序转变为具有明显的占位倾向性;Zr,Nb和Ag元素的占位行为随温度升高没有显著变化.比较表明,Ti/Al比对合金化元素占位行为的影响大于温度的影响.该结果与大部分文献报道的实验和计算结果吻合.     

从芯棒钢的冶炼谈起

宝钢300吨转炉能不能冶炼芯棒钢?这是不少人关心的问题。芯棒钢的化学成分如下(%): C Si Mn P0.36/0.42 0.90/1.00 0.30/0.50≤0.025 S Al Cr Mo≤0.025 ≤0.030 4.80/5.80 0.80/1.00 V0.25/0.50 按德方冶炼方案,除钼采用前装入(随炉料加入炉内)外,其余合金元素全部在钢包中进行合金化。因此,目标出钢温度的考虑方法按下式计算:     

1000MPa级Ti微合金化超细晶冷轧双相钢及其制备工艺

专利号：CN201010034472．0专利权人：北京科技大学本发明是一种1000MPa级Ti微合金化超细晶冷轧双相钢及其制备工艺,属于冷轧超高强汽车用钢技术领域。钢的化学成分质量分数为：C：0．03％～0．20％,Si：0．20％～0．80％,Mn：1．2％～2．0％,Ti：0．0300～0．15％,S％O．015％,P％0．020％,Als：0．02％～0．15％,余量为Fe。本发明以C-Si—Mn—Ti为基本合金系,采用价格低廉的Ti而不添加Cr、Mo、Nb、V等合金元素,降低了生产成本,     

550℃用高温钛合金的研发

应高推比航空发动机的需求,英国、美国、俄罗斯、中国等对高温钛合金进行了大量的研究工作。世界各国研发的550℃用高温钛合金主要有IMI829、Ti-6242S、BT25、BT25Y、Ti-55、Ti-53311S和Ti-633G合金等。简述了这几种合金的合金化特点,介绍了合金化的各种元素在合金中所起的作用,重点阐述了Si元素对合金蠕变性能的影响;同时回顾了这几种钛合金的研发状况、室高温拉伸性能、应用状况,以及稀土元素对部分高温钛合金组织性能的影响等,并展望了其未来的发展趋势与重点研究方向。     

Involvement of tachykinins in endotoxin-induced airway hyperresponsiveness

Three new titanium alloys with Zr, Nb, Ta, Pd and In as alloying elements were developed and compared with currently used implant metals, namely, pure Ti and Ti-6Al-4V alloy, in terms of mechanical and corrosion properties, and cytotoxicity. New alloys showed comparable mechanical properties with that of the Ti-6Al-4V alloy, but increased corrosion potential, somewhat decreased breakdown potential and increased corrosion rate. There were no significant differences in cell growth on the surface of the various metal specimens, indicating that the cells cannot differentiate between the passivated surfaces of the various Ti metals.     

Preparation of TiAl15Si15 intermetallic alloy by mechanical alloying and the spark plasma sintering method

This work is devoted to the preparation of alloys based on intermetallic compounds in the Ti–Al–Si system by powder metallurgy using mechanical alloying and the spark plasma sintering (SPS) method. The aim was to describe the formation of intermetallic phases during mechanical alloying of TiAl15Si15 (wt-%) alloy and to consolidate the powder prepared by optimised conditions. Phase composition, microstructure and hardness of compacted alloy were determined. Four hours of mechanical alloying is sufficient time for preparation of pure elements free material composed only of intermetallic phases. After consolidation, the TiAl15Si15 alloy has a homogeneous structure composed of silicide (Ti₅Si₃) in aluminide (TiAl) matrix. The hardness of the material reaches 865?±?42 HV 5.     

合金元素Sn、Cr对Cu-Si合金组织及力学性能的影响

探讨了添加一定量的合金元素Sn、Cr对Cu-Si合金组织的影响规律,同时比较分析了合金元素的加入对合金力学性能的作用效果.结果表明:Sn、Cr元素均有利于Cu-Si合金加工组织的细化.其中,添加Sn元素对改善Cu-Si合金的力学性能较为明显,经热轧、冷轧(65%变形率)后,其抗拉强度增幅可达22.1%.     

Direct Laser Fabrication of Ti-25V-15Cr-2Al-0.2C (wt?pct) Burn-Resistant Titanium Alloy

Direct laser fabrication has been used to deposit multilayers of burn-resistant titanium alloy onto the surface of Ti697 (Ti-11Sn-5Zr-2.25Al-0.25Si) alloy by feeding Ti-25V-15Cr-2Al-0.2C (wt pct) powder into the laser molten pool. The microstructure and mechanical properties of the deposited layers have been studied to identify the importance of laser conditions on properties/microstructure. The observations are discussed in terms of the optimum laser conditions and thus the potential of using BuRTi (Ti-25V-15Cr-2Al-0.2C) to tip blades of high-temperature titanium alloys to provide burn resistance.     

Influence of Strontium Addition on Microstructure and Mechanical Properties of an Al–10Si–5Cu Alloy

The microstructure and mechanical properties of Al–10Si–5Cu cast alloys with micro-addition of alloying elements (V, Cr and Ni) were studied before and after strontium addition. Samples were examined using the X-Ray diffraction, the optical microscope, the scanning electron microscope and the energy dispersive spectrometer. The results indicated that the α-Al matrix, eutectic Si phase and Al₂Cu phase were the main constituent phases of Al–10Si–5Cu alloys before or after strontium addition. Strontium addition affected the refining of the α-Al grains and transforming the configuration of interdendritic phases. The un-modified alloy showed a brittle nature because of existing brittle and aggregated AlSiMnFe phases. Contributing to the alteration of microstructure in strontium modified alloy, the strength and elongation of the alloy were improved. In addition, the fracture mechanism and crack propagation process were investigated in both the alloys.     

Microstructural characterisation of Ti–Nb–(Fe–Cr) alloys obtained by powder metallurgy

Abstract

β alloys based on the Ti–Nb alloy system are of growing interest to the biomaterial community. The addition of small amounts of Fe and Cr further increases β-phase stability, improving the properties of Ti–Nb alloy. However, PM materials sintered from elemental powders are inhomogeneous due to restricted solid state diffusion and mechanical alloying provides a route to enhance mixing and elemental diffusion. The microstructural characteristics and bend strength of Ti–Nb–(Fe–Cr) alloys obtained from elemental powder mixture and mechanical alloyed powders are compared. Mechanical alloying gives more homogeneous compositions and particle morphology, characterised by rounded, significantly enlarged particles. In the sintered samples α and β phase are observed. The α phase appears at the grain boundaries and in lamellae growing inward from the edge, and is depleted in Nb. The β phase is enriched with Nb, Fe and Cr. The addition of Fe and Cr significantly increases the mechanical properties of Ti–Nb alloys, providing increased ductility.     

Effect of Iron Content on Sintering Behavior of Ti-V-Fe-Al Near-β Titanium Alloy

Two near-β Ti-10V-3Fe-3Al and Ti-10V-2Fe-3Al alloys were produced by blended elemental powder metallurgy using hydrogenated titanium and V-Fe-Al master alloy powders. The distributions of the alloying elements were investigated at different stages of transformation of the heterogeneous powder compacts into the final homogeneous alloy product. The influence of iron content on chemical homogenization, densification, microstructure, and mechanical properties of as-sintered alloys was discussed with respect to the fast diffusion mobility of iron in titanium. It was concluded that a 1 pct increase in Fe content, as the alloying element with the fastest diffusivity in titanium, has a positive effect on densification. However, this also results in some grain coarsening of the final material. The attained mechanical properties were comparable with those of cast/wrought near-beta titanium alloys.     

Use of Alloying to Effect an Equiaxed Microstructure in Additive Manufacturing and Subsequent Heat Treatment of High-Strength Titanium Alloys

This paper addresses the use of alloying additions to titanium alloys for additive manufacturing (AM) with the specific objective of producing equiaxed microstructures. The additions are among those that increase freezing ranges such that significant solutal undercooling results when combined with the rapid cooling rates associated with AM, and so be effective in inducing a columnar-to-equiaxed transition (CET). Firstly, computational thermodynamics has been used to provide a simple graphical means of predicting these additions; this method has been used to explore additions of Ni and Fe to the alloy Ti–6Al–4V (Ti64). Secondly, an experimental means of determining the minimum concentration of these alloying elements required to effect the CET has been developed involving gradient builds. Thirdly, it has been found that additions of Fe to Ti64 cause the alloy to change from an α/β Ti alloy to being a metastable β-Ti alloy, whereas additions of Ni do not produce the same result. This change in type of Ti alloy results in a marked difference in the development of microstructures of these compositionally modified alloys using heat treatments. Finally, hardness measurements have been used to provide a preliminary assessment of the mechanical response of these modified alloys.