Ultrasonic measurement of the kearns texture factors in zircaloy, zirconium, and titanium

Texture, developed during the processing of zirconium and zirconium alloys, e.g., ZIRCALOY, plays an important role in determining the properties and performance of the resultant structural components. Extending the work done on cubic metals, ultrasonic velocity measurements were used to nondestructively characterize the texture in hexagonal sheet metals. A theory is developed relating the texture coefficients W _LMN (L≤4, found in an expansion of the crystallite orientation distribution function (ODF) in terms of generalized spherical harmonics) to industrially measured Kearns factors, which predict the fraction of basal poles aligned in a particular sample reference direction. Ultrasonic characterization of texture has been performed on three sheets of zirconium (one pure, two ZIRCALOY) and on one sheet of titanium. These results are compared to the Kearns factors, measured by X-ray diffraction (for the two ZIRCALOY sheets) and to the W _LMN value measured by neutron diffraction (for the pure zirconium and the titanium). Results show that ultrasonics predict both the orientation distribution coefficients (ODCs) and the Kearns factors very well.     

The resistivity of refractory compounds at high temperatures

Summary The authors measured the temperature dependence of the electrical resistance of carbides of titanium, zirconium, hafnium, niobium, molybdenum and tungsten and borides of titanium and zirconium. The thermal coefficients of the electrical resistance were calculated for the measured carbides and borides. Attempts were made to correlate the values of the electrical resistances with the electron structure of the compounds.     

Zirconium Dodecaboride-based cutting material

Samples of zirconium dodecaboride are obtained by means of arc and induction melting of a mixture of zirconium and boron powders. A solder for binding the zirconium dodecaboride to the steel holder of the tool is selected. It is established that cutting tools supplied with zirconium dodecaboride may be used in operations of finish turning of adhesive-active titanium alloys.     

Zirconium Dodecaboride-based cutting material

Samples of zirconium dodecaboride are obtained by means of arc and induction melting of a mixture of zirconium and boron powders. A solder for binding the zirconium dodecaboride to the steel holder of the tool is selected. It is established that cutting tools supplied with zirconium dodecaboride may be used in operations of finish turning of adhesive-active titanium alloys.     

Reaction of tungsten carbide with oxides of refractory metals in a vacuum

Summary An investigation was made into the kinetics of the reaction of tungsten carbide with niobium, tantalum, vanadium, titanium, chromium, and zirconium oxides. Low-carbon alloys of tungsten with niobium, tantalum, chromium, and vanadium were produced. A method of preparing refractory alloys, using an oxide-carbide mixture as an intermediate product, has been proposed.     

Thermodynamics of the oxygen solutions in zirconium-containing iron-nickel melts

Thermodynamic analysis of the oxygen solutions in zirconium-containing iron-nickel melts is carried out. The equilibrium deoxidation constants of the melts by zirconium, the activity coefficients at infinite dilution, and the interaction parameters in melts of various compositions are determined. The dependences of the oxygen solubility in the melts on the nickel or zirconium content are calculated. Zirconium is shown to possess a very high deoxidizing capacity in iron-nickel alloys. The zirconium contents at the minima in oxygen solubility curves and the corresponding minimum oxygen concentrations are determined. As the nickel content in a melt increases to ∼45%, the deoxidizing capacity of zirconium decreases and, then, increases. The deoxidizing capacity of zirconium in pure nickel is noticeably higher than that in pure iron.     

Relationship between contractile strain ratioR and texture in zirconium alloy tubing

The crystallographic textures of zirconium alloy tubing used as cladding in nuclear reactor fuel are commonly characterized by the quantitative texture numbersF (Källström) and f_r (Kearns) which are derived from the direct and inverse pole figures. The texture numbers of zircaloy 2 and 4 tubes have been correlated experimentally with the value of the contractile strain ratioR which is a measure of the plastic anisotropy of the tube. The correlations were based on the results of 20 different tubing lots. Thef _r-R correlation shows much less data scatter than theF-R correlation. By assuming a simple plastic deformation model for zirconium alloys the following relations between texture and anisotropy are obtained:F=R- 1/R+1 and f_r = R/R+1 The theoretically derived relations are in good agreement with the experimental data. The procedure of correlating texture with plastic anisotropy is not limited to zirconium alloy tubing, but should be equally applicable to textured sheet and plate materials and other alloys with a limited number of slip systems.     

Thermodynamics of inclusion formation in Fe-Cr-Ti-N alloys

The thermodynamics of titanium in Fe-Cr alloys and of inclusion formation in Fe-Cr-N-Ti alloys was investigated. A metal-nitride-gas equilibration technique was used to measure the activity of titanium. The equilibrium titanium content of the metal that is in equilibrium with pure solid titanium nitride and nitrogen gas at 1 atm was determined. The activity coefficients of titanium it(f_Ti) relative to 1 wt pct standard state in Fe were calculated for Fe-Cr alloys from the experimental results. The first-order interaction coefficient between titanium and chromium, e _Ti ^Cr , was determined to be 0.024 at 1873 K. The solubility of nitrogen in Fe-Cr alloys was measured and was found to increase with chromium content, which is in agreement with previous work. Thermodynamic calculations were made in order to predict under what conditions titanium nitride will form in 409 stainless steel and was compared with inclusions found in plant samples. The inclusion stability diagrams for 304 stainless steel and Fe-18 pct Cr and Fe-9 pct Cr alloys were computed.     

电感耦合等离子体原子发射光谱法测定锆及锆合金中钛

探讨了电感耦合等离子体原子发射光谱法(ICP-AES)测定锆及锆合金中钛的条件并建立了测定方法。采用盐酸、氢氟酸和硝酸溶解试样, 选择波长339.4 nm(样品不含铌时)和338.3 nm(样品含铌时)的谱线作为钛分析线, 在选定的仪器工作条件下对试液中钛进行测定。锡、铁、铬、镍对钛的测定无影响, 基体元素锆和合金元素铌对钛测定的影响可以分别采用基体匹配和选择不同波长谱线作为钛分析线的方法克服。在选定的仪器工作条件下, 对锆及锆合金试样中钛含量进行多次测定, 结果与分光光度法(GB/T13747.1992)、直流电弧原子发射光谱法的测定结果基本一致, 相对标准偏差(n=9)均小于15%。方法的精密度和准确度均满足科研生产的检测要求。     

Thermodynamic properties of titanium and iron in molten silicon

Titanium and iron in silicon are known as harmful “lifetime killer” impurities, which shorten the lifetime of excited carriers in silicon solar cell and disturb power generation. Therefore, the removal of titanium and iron is one of the most important topics for the production of solar grade silicon. Thermodynamic properties of titanium and iron in molten silicon were determined at 1723 K by equilibrating molten silicon-titanium alloys or molten silicon-iron alloys with molten lead, which has a limited mutual solubility for both alloys. The activity coefficients of infinite dilution, self-interaction coefficients of titanium and iron in molten silicon, and the Gibbs energy change of mixing for silicon-titanium and silicon-iron at 1723 K relative to pure liquid silicon, titanium, and iron were determined.     

Tin-based reactive solders for ceramic/metal joints

Contact angle measurements on silicon-nitride substrates were conducted on tin-based alloys, containing titanium and zirconium, to determine the suitability of these alloys as filler metals for low-temperature joining of ceramics. Titanium-containing alloys exhibited excellent wettability characterized by contact angles less than 20 deg, whereas the Zr-containing alloys exhibited contact angles around 50 deg. The superior wettability of the Sn−Ti alloys is attributed to the higher activity coefficient of Ti in Sn−Ti alloys. The liquidus temperature of the Sn−Ti alloys is in the 400°C to 600°C range. Hence, these alloys are expected to reduce the residual stress problem.     

Criteria of Grain Refinement Induced by Ultrasonic Melt Treatment of Aluminum Alloys Containing Zr and Ti

It is well known that ultrasonic melt treatment (UST) promotes grain refinement in aluminum alloys. Cavitation-aided grain refinement has been studied for many years; however, it is still not being applied commercially. The current article summarizes the results of experimental work performed on various alloying systems at different stages of solidification. The influence of UST parameters and solidification conditions on the final grain structure is analyzed. It was found that small additions of zirconium and titanium can significantly increase the efficiency of UST, under the stipulation that grain refinement is performed in the temperature range of primary solidification of Al₃Zr. The possible mechanisms for this effect are discussed.     

The influence that a zirconium additive has on the strength and electrical resistance of cold-rolled aluminum sheets

The influence that a Zr additive (0.3–0.6 wt %) and annealing modes have on the electrical resistance and mechanical properties of cold-rolled sheets obtained from cast ingots on the basis of technical grade A7E aluminum is investigated. It is shown that all zirconium-doped alloys retain deformation strengthening after 1-h annealing at 300°C, in contrast to undoped aluminum. In this case, as the Zr concentration increases, the strength properties improve, which may be associated with the summation of two effects: deformation and dispersion. It is established that, as the Zr content increases, the resistance of cold-rolled sheets substantially increases; however, after annealing, this characteristic is first of all determined by the zirconium concentration in the aluminum-based solid solution and depends on the parameters of heat treatment.     

电感耦合等离子体原子发射光谱法测定钛合金中钼锆铌

对于0.100 g钛合金试样,加入10 mL 硫酸(1+1)和2～3 滴硝酸可将钛合金溶解成清亮的、能够长期稳定存在的溶液。通过研究钛合金中钼、锆、铌的谱线干扰情况,选择钼 202.031 nm、锆339.197 nm和铌 269.706 nm为分析线,实现了电感耦合等离子体原子发射光谱法(ICP-AES)对钛合金中钼、锆、铌的测定。通过采用钛合金国家标准物质按照试样处理方法和采用钛打底加入钼、锆、铌标准溶液制备而成的系列钼、锆、铌标准溶液分别绘制校准曲线,所得校准曲线相关系数(r)均大于0.999。但因市场上同时含有钼、锆、铌的钛合金标准物质不多,建议采用钛打底加入钼、锆、铌标准溶液的方式进行标准系列溶液的配制。各元素的检出限均不大于0.005%。采用两种标准溶液配制方式绘制校准曲线,对同一个钛合金样品进行精密度考察,结果的相对标准偏差(RSD,n=10)均小于1.0%。采用实验方法分析国家标准物质,测定值与认定值一致,误差在国标允许误差范围内,能够满足生产和科研的需要。方法适用于含铌不超过5%的钛合金的测定。     

SPD技术对锆及锆合金力学行为影响研究现状

综述了锆及锆合金剧烈塑性变形(SPD)后性能变化的研究进展,系统阐述了锆及锆合金经剧烈塑性变形后显微硬度、拉伸/压缩性能、高低周疲劳性能,重点介绍了SPD技术在纯锆、Zr-Nb系合金中的应用.经过剧烈塑性变形后,锆及锆合金的抗拉强度及屈服强度均显著提升,但依据剧烈塑性成形轨迹、合金成分、第二相分布、热处理制度不同,其提...     

包覆热轧制备粉末冶金TiAl合金板材及热加工行为研究

采用超声气体雾化法制备洁净的TiAl预合金粉末,再经粉末除气、封装、热等静压致密化等工序获得TiAl基合金热轧板坯,之后包覆热轧制备粉末冶金TiAl基合金板材。轧制过程中材料的应变、应力状态、温度场分布非常复杂,本实验采用Gleeble热模拟试验机和有限元（FEM）模拟相结合,确定热加工工艺窗口,优选出热轧工艺参数,并热轧得到组织均匀、性能良好、尺寸为220mm×370mm×2mm的粉末冶金TiAl基合金板材。板材室温拉伸性能Rp0.2为608MPa,Rm为668MPa,A为2．56％;1000℃拉伸性能只眦为163MPa,Rm为330MPa,A为32．0％;焊接成形性良好,焊缝无缺陷及二次裂纹产生,焊缝区域显微组织与基体差别不大。     

The effects of molybdenum and aluminum on the thermal expansion coefficients of nickel-base alloys

The effects of molybdenum and aluminum on the mean linear thermal expansion coefficients from room temperature to 1050°C were determined for two types of nickel-base alloys. The Solid Solution Alloys were cast and homogenized Ni-Co-Cr-Mo alloys with 0, 312, and 612 nominal wt pct molybdenum concentrations. The Gamma Prime Alloys were wrought and heat-treated Ni-Cr-Mo-Al(Ti) alloys with 0, 2, 5, and 8 nominal wt pct molybdenum in each of four aluminum plus titanium levels (3 pct Al, 412 pct Al, 6 pct Al, or 1 pct Al + 312 pct Ti nominal wt pct). Thermal expansion coefficients were determined on at least two specimens from each alloy. It was found that molybdenum lowers the thermal expansion coefficients of both the cast Ni-Co-Cr solid solutions and the wrought Ni-Cr-Al(Ti) two-phase alloys. Both aluminum and titanium were also observed to decrease expansion coefficients in the two-phase, γ + γ, alloys. Results are discussed in terms of relative melting point effects between solute and solvent elements, and in terms of the volume fraction of the γ phase present.     

The effects of molybdenum and aluminum on the thermal expansion coefficients of nickel-base alloys

The effects of molybdenum and aluminum on the mean linear thermal expansion coefficients from room temperature to 1050°C were determined for two types of nickel-base alloys. The Solid Solution Alloys were cast and homogenized Ni-Co-Cr-Mo alloys with 0, 312, and 612 nominal wt pct molybdenum concentrations. The Gamma Prime Alloys were wrought and heat-treated Ni-Cr-Mo-Al(Ti) alloys with 0, 2, 5, and 8 nominal wt pct molybdenum in each of four aluminum plus titanium levels (3 pct Al, 412 pct Al, 6 pct Al, or 1 pct Al + 312 pct Ti nominal wt pct). Thermal expansion coefficients were determined on at least two specimens from each alloy. It was found that molybdenum lowers the thermal expansion coefficients of both the cast Ni-Co-Cr solid solutions and the wrought Ni-Cr-Al(Ti) two-phase alloys. Both aluminum and titanium were also observed to decrease expansion coefficients in the two-phase, γ + γ, alloys. Results are discussed in terms of relative melting point effects between solute and solvent elements, and in terms of the volume fraction of the γ phase present.     

The mechanisms of grain refinement in dilute aluminum alloys

The contribution of the peritectic reaction in producing grain refinement in aluminum alloys has been studied in three binary aluminum systems. It appears that titanium has a unique effect compared with zirconium or chromium; there is evidence of a refinement mechanism associated with the peritectic reaction in Al?Ti alloys which was not observed in the other two systems. Additions of boron to Al?Ti and Al?Zr alloys emphasizes the difference in effect of these two transition elements as grain refiners. The significance of the present work is discussed with reference to conflicts apparent in earlier experimental data.     

低成本高性能钛合金研究进展

基于钛合金材料在新一代航空航天飞行器上大量使用,以满足减重、延长寿命的设计和使用要求,因此钛合金低成本化以及钛合金材料成形的低成本化已成为国内外钛工业领域研究的重要方向。发展具有我国自主知识产权的航空用高性能低成本钛合金材料及其加工技术,是提高我国钛合金材料在航空领域用量和应用水平的重要途径。介绍了国内外主要钛合金生产国一些低成本钛合金的研发背景、典型力学性能以及实际应用情况,指出了降低航空用高性能钛合金材料的发展思路。