Grain refinement effects of Al based alloys with low titanium content produced by electrolysis

A series of Al based alloys with low titanium contents (mass fraction) from 0.178% to 0.526% were directly produced in ordinary industrial electrolyzer. The electrolyzing results show that producing Al based alloys with titanium contents of less than 0.30% without great loss of electrolysis efficiency is possible. The quantitative analysis shows that this method has a great refining effect on transiting the coarse columnar grains in pure Al to equiaxed grains. The grain sizes decrease with the increase of titanium content and tend to a low limit at about 130 μm. During the solidification, the non equilibrium distribution of titanium leads to a great growth restricting effect and a constitutional under cooling zone in front of the growing liquid /solid interface.

Estimation of lunar titanium content: Based on absorption features of Chang’E-1 interference imaging spectrometer (ⅡM)

Two linear regression models based on absorption features extracted from CE-1 IIM image data are presented to discuss the relationship between absorption features and titanium content. We computed five absorption parameters (Full Wave at Half Maximum (FWHM), absorption position, absorption area, absorption depth and absorption asymmetry) of the spectra collected at Apollo 17 landing sites to build two regression models, one with FWHM and the other without FWHM due to the low relation coefficient between FWHM and Ti content. Finally Ti content measured from Apollo 17 samples and Apollo 16 samples was used to test the accuracy. The results show that the predicted values of the model with FWHM have many singular values and the result of model without FWHM is more stable. The two models are relatively accurate for high-Ti districts, while seem inexact and disable for low-Ti districts.

Titanium Content Control for Bearing Steel

On the basis of the thermodynamic analysis and fundamental study in the laboratory, the equilibrium of the Ti A10 system was investigated. The results showed that the equilibrium titanium content in the steel increased with the increase in the soluble aluminum content in the steel and the TiO2 content in the slag. Although the slag basicity decreased and Al2O3 content in the slag increased, the titanium content increased. Based on these results, the BOF smelting process of low titanium bearing steel was put forward.

Dynamic stress–strain properties of Ti–Al–V titanium alloys with various element contents

A series of Ti–Al–V titanium alloy bars with nominal composition Ti–7Al–5V ELI,Ti–5Al–3V ELI,commercial Ti–6Al–4V ELI and commercial Ti–6Al–4V were prepared.These alloys were then heat treated to obtain bimodal or equiaxed microstructures with various contents of primary a phase.Dynamic compression properties of the alloys above were studied by split Hopkinson pressure bar system at strain rates from 2,000 to 4,000 s-1.The results show that Ti–6Al–4V alloy with equiaxed primary a(ap)volume fraction of 45 vol%or 67 vol%exhibits good dynamic properties with high dynamic strength and absorbed energy,as well as an acceptable dynamic plasticity.However,all the Ti53ELI specimens and Ti64ELI specimens with ap of 65 vol%were not fractured at a strain rate of4,000 s-1.It appears that the undamaged specimens still have load-bearing capability.Dynamic strength of Ti–Al–V alloy can be improved as the contents of elements Al,V,Fe,and O increase,while dynamic strain is not sensitive to the composition in the appropriate range.The effects of primary alpha volume fraction on the dynamic properties are dependent on the compositions of Ti–Al–V alloys.

Influence of Coke Content on Sintering Process of Chromium-containing Vanadium-titanium Magnetite

The sintering of chromium-containing vanadium-titanium magnetite using different coke contents was studied through the sintering pot tests, X-ray diffraction analysis and mineralogical phase analysis. Results showed that, as the coke content increased from 3.2% to 4.4%, the liquid phase and combustion zone thickness increased while the vertical sintering rate and ratio of sintered product decreased. In addition, the combustion ratio of exhaust gas also increased with increasing the coke content, indicating that combustion zone temperature also increased, and the excessive the coke content in the sintering process of vanadiumtitanium magnetite is harmful. As the coke content increased, the magnetite, silicates, and perovskite contents of the sintered ore increased while the contents of hematite and calcium ferrite of sintered ore decreased; drum strength decreased, and reduction degradation properties increased while reduction ability decreased. We found that the appropriate coke content for the sintering process is 3.6 wt%.

Influence of interstitial content on mechanical properties of new type of near α titanium alloy at cryogenic temperature

The influence of interstitial content on mechanical properties of a new type of near α titanium alloy(Ti-Zr-Mo-Nb-Sn) at cryogenic temperature was studied. The results show that interstitial content affects the mechanical properties of the alloy at cryogenic temperature. Interstitial element atoms solving into lattice causes the increasing of degree of distortion,which limits the sliding and twinning of dislocations. Reducing interstitial content is beneficial to generation of dislocation sliding and deformation twins. With interstitial element content reducing,the impact toughness and the elongation of the alloy decrease rapidly while the strength decreases weakly. To obtain good over-all properties at cryogenic temperature,the interstitial element content in this alloy must be controlled to extra low grade.

Effects of alloying elements on nitrogen diffusion behavior around TiN/Ti interface α region in as-cast titanium alloys

To characterize the effects of alloying elements on inclusion dissolution of titanium nitride, the content profiles of elements around TiN/Ti boundary α phase regions in liquid titanium alloys have been experimentally carried out. Four kinds of commercial alloys of CpTi, Ti64, Ti17 and Ti6242 containing different α stabilizing or β stabilizing elements are examined through artificially embedding the TiN sponge particle into liquid alloys in VAR conditions. The content profiles of nitrogen and alloying elements around TiN/Ti boundary were measured by WDX and microprobe for as cast samples. The content profiles of nitrogen and alloying elements around N containing solid in α Ti region of these alloys show a common features of a steep change. In particular, the content profiles of elements for Ti6242 demonstrate unique change of a more gentle change tendency and further deeper into the alloy matrix. The experiment results show that, the differences among composite effects of alloying elements in different alloys within nitrogen induced diffusion α region result in different dissolution and diffusion behaviors to overcome the α phase region barriers.

Deposition of Titanium Layer on Steel Substrate Using PECVD Method: A Parametric Study

Metallic titanium film was deposited on H-13 steel substrate at 470°C - 530°C using plasma enhanced chemical vapor deposition (PECVD) method. In this paper, the effects of manufacturing parameters were investigated on deposited titanium coating characteristics. XRD, FESEM, XPS and AFM were used in order to study coating characteristics. Increasing hydrogen flow rate from 200 to 360 sccm, resulted in a 72% decrease in oxygen content and 38% decrease in chlorine content of the film. Applied plasma voltage has a severe effect on nanohardness of coating. Pressure of the deposition chamber has a negative effect on titanium characteristics.

添加稀土元素的TC4钛合金激光焊接头纵向超塑性能研究

针对钛合金激光焊接接头超塑性能低的难题,提出在焊缝中以Yb_(2)O_(3)的方式添加稀土Yb元素,分析Yb_(2)O_(3)含量对TC4钛合金激光焊接头高温拉伸峰值流变应力、断后伸长率及组织的影响.结果表明,Yb_(2)O_(3)能够促进变形过程的组织等轴化进程,减小焊缝β晶粒尺寸和接头超塑性变形流变应力,并提高断后伸长率.随着Yb_(2)O_(3)含量增加,接头应力应变曲线下移,峰值流变应力呈先降低后升高的趋势,而断后伸长率则为先增大后减小.在超塑性变形过程中,Yb_(2)O_(3)含量6%时峰值流变应力最低为11.9 MPa,断后伸长率为572.3%;焊缝中心β晶粒尺寸最小为127μm,相较于未添加Yb_(2)O_(3)时β晶粒尺寸的337μm细化了62.3%.此时,马氏体组织发生相变,形态转变成片层,焊缝区域组织等轴化程度最高,焊缝的超塑性能最好.

3D打印钛合金的制备与组织性能研究

采用3D打印的方法制备了不同C含量(质量分数)的Ti-4Al-3V-x C钛合金(x=0,0.12,0.23,0.39和0.62),对比分析了不同C含量钛合金的显微组织、硬度、蠕变性能和拉伸性能。结果表明,添加C的钛合金的硬度和弹性模量都高于未添加C的钛合金,且随着C含量从0.12%增加至0.62%,含C钛合金的硬度和弹性模量逐渐增加;随着保压时间的延长,不同C含量的钛合金的蠕变深度都呈现逐渐增加的趋势,但是在相同保压时间下,含C钛合金的蠕变深度都小于不含C钛合金,且C含量越高则钛合金的蠕变深度越小。含C钛合金的抗拉强度和屈服强度都高于不含C钛合金,而断后伸长率都低于不含C钛合金,尤其是当C含量增加至0.39%及以上时,含C钛合金的断后伸长率下降较为明显。当C含量为0.23%时,3D打印钛合金的抗拉强度、屈服强度和断后伸长率高于铸造TC4钛合金和锻态TC4钛合金,具有相对较好的综合性能。

钛白副产硫酸亚铁中镁离子的含量分析

本文研究以酸性铬蓝K为指示剂,以草酸铵为沉淀剂排除Fe^(2+)干扰,用紫外分光光度法测定钛白副产物FeSO_(4)中的Mg^(2+)的含量。实验结果表明,Mg-铬蓝K的最大吸收峰波长为540nm,最佳pH值为9.5,最佳沉淀剂草酸铵的用量为10mL。经加标回收的方法验证了方法的可行性,测出钛白副产物FeSO_(4)中Mg^(2+)含量为1.07%。

钛含量对锻压态机械壳体镁合金性能的影响

为了研究钛(Ti)含量对锻压态机械壳体Mg-6Al-4Sn-Ti镁合金耐磨损性能和耐腐蚀性能的影响,优化Mg-6Al-4Sn-Ti镁合金中的钛含量,制备了锻压态Mg-6Al-4Sn-xTi(x=0,0.1,0.2,0.3,0.4,0.5(质量分数,%))镁合金试样,并进行了合金显微组织、耐磨损性能和耐腐蚀性能的测试与对比分析。结果表明:合金元素Ti有助于细化锻压态Mg-6Al-4Sn镁合金晶粒、提高合金耐磨损性能和耐腐蚀性能。随着合金元素Ti含量从0逐渐增加到0.5%,合金晶粒先细化后粗化,磨损体积先减小后增大,腐蚀电位先正移后负移,耐磨损性能和耐腐蚀性能均先提高后下降。与不添加Ti的锻压态Mg-6Al-4Sn镁合金相比,添加0.3%Ti的锻压态Mg-6Al-4Sn-Ti镁合金磨损体积减小幅度达21%、腐蚀电位正移幅度达13%。锻压中机械壳体Mg-6Al-4Sn-xTi镁合金的合金元素Ti含量优选为0.3%。

高Al含量的亚稳β型Ti-Al-Mo-Nb-V系列钛合金的组织与力学性能

目前,亚稳β钛合金的成分朝着更高Al含量和更高β稳定元素含量的方向发展,本工作基于典型亚稳β钛合金β-21S和TB18的成分设计思路,添加了更高含量的Al元素,同时添加了Mo、Nb、V三种β稳定元素,设计并利用铜模吸铸法制备了高Al含量的亚稳β型Ti-Al-(Mo,Nb,V)系列钛合金。结果表明,Ti-6.5Al-1.5V-11.5Mo-2.8Nb合金在吸铸态下的β相结构达到临界稳定状态。此时,该合金的拉伸屈服强度为623 MPa,延伸率为16.6%,其屈服强度略低于对标合金TB18,但延伸率明显高于同系列合金和TB18合金,具有最佳的综合力学性能。此外,该合金液固温区为31℃,在同系列合金中最低,且明显低于对标合金TB18的液固温区238℃。

粘结剂和碳化钛含量对TiC钢结硬质合金组织和性能的影响

立足于碳化钛钢结硬质合金大批量生产的实践基础,探讨了使用不同粘结剂以及碳化钛的不同含量对钢结硬质合金的微观组织和宏观性能的影响。实验表明,在相同的压制成型工艺下,采用不同的粘结剂,在1380~1420℃真空烧结后,钢结硬质合金的致密度较高,都达到了预期的组织和性能,但是相对而言,使用橡胶基粘结剂的产品性能更稳定;不同碳化钛含量的钢结硬质合金,在1350~1420℃真空烧结后,钢结硬质合金同样都达到了预期的组织和性能,随着碳化钛在基体中的分布均匀性提高,颗粒形貌更加规则。

力学性能可调的高氧钛原位电弧增材制造

通过电弧增材制造原位制备高氧钛,并对高氧钛的成分偏析、显微组织和力学性能进行研究。结果表明,高氧钛试样的显微组织主要呈现为针状α相集束。随着氧含量的增加,试样针状α相逐渐变宽,集束尺寸变大。受氧的强化作用以及晶粒尺寸效应共同影响,试样的强度先提高后下降,伸长率显著下降,断裂形式由塑性断裂向解理断裂过渡。当氧含量达到0.37%(质量分数)时,伸长率约为7%,试样抗拉强度超过730 MPa,约为商业纯钛的2倍。

高钛高强钢钛含量精准控制研究

对高钛高强钢的冶炼流程进行了分析,针对存在的问题进行了理论与实践相结合的研究,制定相应的改进措施。通过控制真空室内的氧和钢液中的氧含量,提高高钛钢铸机成品目标值w(Ti)±0.005%合格率。

X射线能谱法与分光光度法测定聚酯切片中二氧化钛含量的比较分析

采用了UV 2450分光光度仪和EDX-8000 X射线能谱仪分别测定了聚酯切片中的二氧化钛含量,对比分析了2种分析方法的操作条件。结果表明,X射线荧光度法的线性相关性、准确度、精密度均优于分光光度法,分析时间也由70 min缩短到30 min,并且二氧化钛的加标回收率能达到98%~102%,相对标准偏差为0.49。

固溶温度对Ti6321钛合金组织及显微硬度的影响

本文对Ti6321板材进行固溶处理,并对固溶处理后的组织进行显微硬度测试。研究了固溶温度对组织形貌及相含量的影响,分析了显微组织与显微硬度的关系。结果表明,随固溶温度升高初生α相含量明显下降,Ti6321钛合金热轧板材的显微组织发生由等轴组织到双态组织,再到魏氏组织的转变;未热处理的Ti6321钛合金显微维氏硬度为317.2HV,随固溶温度升高,显微维氏硬度先增大随后基本保持不变,在固溶温度为900℃时显微维氏硬度达到最大值338.6HV。

氧含量对激光定向能量沉积Ti-6Al-4V钛合金组织和性能的影响

采用激光能量沉积法制备了TC4钛合金试样块,借助OM、SEM、电子探针定量分析、X射线衍射等方法,研究了不同氧含量对钛合金微观结构、相组成、氧气浓度及性能之间的相关性。结果表明,衍射峰的强度随着氧含量的增加而略有增加。而(002)衍射峰的强度明显在中氧环境下达到最大,随之减弱。材料的强度和硬度随着氧含量的增加分别提高115 MPa和58 HV,伸长率下降到8.71%,断面收缩率下降到6.6%。断裂失效机制随着氧含量的增加由韧性断裂转变为准解理与韧性断裂复合断裂。宏观组织主要为柱状晶粒和针状马氏体为主,热处理后主要是马氏体α'和β转组织。不同氧含量环境下形成的间隙固溶体,导致晶格常数增大,从将引起晶格膨胀。随着界面能量的增加,进而在晶界生成高密度位错现象,对钉扎起到进一步加强作用,使试样强度提高而塑性降低。

因素条件对红外吸收法测试钛合金中氢含量的影响

本文采用脉冲炉惰性气体熔融红外吸收法测试钛合金中氢含量。研究样品处理方式、样品放置时间、样品存储方式、超声时间、样品清洗剂种类、分析功率、助熔剂用量7种因素条件对钛合金氢含量测试的影响。确定了红外吸收法测试钛合金中氢含量的试验条件:精密车床或者酸洗处理样品,采用丙酮或者无水乙醇超声清洗试样1min,冷风吹干后室温密封保存,采用分析功率3500W、半片锡片助熔剂,尽量4h内分析完试样,实现了红外吸收法测定钛及钛合金中氢含量测试,测定结果在标准值的不确定度范围内,相对标准偏差小于4%(RSD,n=6的分析结果),同时采用该方法测定钛及钛合金样品的氢含量具有操作简便、测试效率高、成本低、稳定性好、准确度高等优点。