锆合金的织构及其对性能的影响

锆合金被广泛应用于核反应堆中，作为燃料元件的包壳材料或堆内结构部件，织构会影响其众多的应用性能，因此织构的研究及控制在锆合金的开发利用中具有重要作用。综述了，锆合金塑性变形的滑移和孪生系统；锆合金管板材的织构特点及控制方法；热轧温度对锆合金板材织构的影响以及退火处理锆合金织构的演化；并分别总结了织构与锆合金屈服强度、蠕变强度、碘致应力腐蚀开裂、氢化物取向分布以及辐照生长等性能的相互关系。     

稀土镁锆中间合金中锆的测定

采用EDTA滴定法测定了稀土镁锆中间合金中的锆.实验确定了合金分解方法及锆滴定时的酸度及温度条件,分析了基体及杂质铁的干扰及消除.分析结果相对标准偏差小于2.5%,标加回收率为98.9%～101.8%.     

等径角挤压和离子渗氮处理医用钛、锆基合金

目前,钛、锆基合金用于外科植入材料的主要瓶颈是力学性能和摩擦性能较差。为得到具有优异综合性能的钛、锆基可植入材料,研究了等径角挤压和离子渗氮处理对钛及锆合金组织和性能的影响。实验以BT1-00钛合金、精炼的锆和锆-铌合金为研究对象,所有试样经表面磨光后的光洁度均达到     

锆和锆合金化学分析标准方法的进展

本文评述了20多年来锆和锆合金化学分析标准方法的进展．对中、美、日等国的分析方法进行了比较，比较的内容：1．要求控制分析的合金成分与杂质元素的数量；2．各元素进行分析时所用的分析方法．并对下列问题进行了讨论；1．仪器分析是现代分析化学的主要标志；2．痕量杂质成分的测定更受重视；3．合金元素的允许偏差4．论证标准分析方法的实用性；5．锆合金标样的必要性；6．重点讨论建立锆和锆合金化学分析企业标准方法的必要性。     

锆基块体非晶合金力学性能的研究进展

锆基块体非晶合金具有优良的非晶形成能力,可在很小的冷却速率条件下获得.锆基非晶合金具有高强度、超塑性、高弹性、高硬度、高耐磨性和高耐腐蚀性能等,有着广阔的应用前景.总结了锆基非晶合金的形成机制,着重对锆基非晶合金的力学性能、耐腐性能等进行了综述.     

浅谈核级海绵锆中氯化物对锆合金铸锭的影响

叙述了核级海绵锆的生产工艺和氯化物对锆合金铸锭的影响。针对在锆合金铸锭生产过程中氯化物对自耗电极焊接及熔炼铸锭的的影响,提出了一系列控制和预防措施,以提高锆合金铸锭生产的安全性和产品质量。     

锆合金研究进展及我国核电站用锆材国产化的思考

综合评述了国内外核电站用锆合金材料的研究进展,重点介绍了目前国际上发展成熟的高性能锆合金：法国的M5合金、美国的Zirlo合金、俄罗斯的E635合金、日本的NDA合金及韩国的HANA合金。分析了我国在核电站用锆合金材料研制过程中存在的问题,以及我国核电用锆材国产化的难点。对我国核电用锆材的发展思路提出了几点建议。     

锆及其化合物的应用

锆及其化合物作为新能源、新材料,具有相当重要的意义。锆合金优异的核性能,成为核燃料包壳管的首选材料;氧氯化锆是生产金属锆、氧化锆和其他锆化合物的中间产品;氧化锆具有增韧的特性,极好的力学性能,是结构陶瓷的最好材料。     

锆和钪对Al-Mg铸造合金组织和力学性能的影响

通过金相显微镜、拉伸力学性能测试、XRD等手段研究了在铸造Al-Mg合金中添加不同含量的钪和锆后合金的铸态组织。结果表明,合金添加钪和锆后,明显减小了枝晶网胞尺寸,细化了晶粒。当锆和钪的添加量分别为0.2%、0.4%时,铸造Al-Mg合金组织具有良好的综合性能。     

丁二酮肟分光光度法测定锆及锆合金中镍

采用氢氟酸-硝酸体系溶解试样,硼酸饱和溶液中和试样溶解后体系中过量的氢氟酸,再以柠檬酸为络合剂,碘为氧化剂,丁二酮肟为显色剂,基于丁二酮肟与镍形成酒红色络合物,建立了锆及锆合金中镍含量的测定方法。重点考察了氢氟酸用量对测定的影响,结果表明,采用以下氢氟酸用量可保证试样溶解完全:当试样量不大于1.0g时,选用2.5mL氢氟酸;当试样量为2.0g时,选用5.0mL氢氟酸。对实验条件进行优化,结果表明,在优化的实验条件下,镍的质量分数在0.002%~0.15%范围内与其吸光度呈线性关系,相关系数为0.9999,方法的检出限为0.01μg/mL,测定下限为0.04μg/mL。考察了锆基体与共存元素对镍测定的影响,结果表明:锆基体与共存元素对镍的测定无影响。按照实验方法测定锆合金标准样品和4种锆及锆合金合成试样中镍,测定结果与电感耦合等离子体原子发射光谱法(ICP-AES)基本一致,且锆合金标准样品测定结果与认定值一致,所测结果的相对标准偏差(RSD,n=11)为2.9%~10.5%。     

The effect of alloy chemistry and heat treatment on the low cycle fatigue behavior of 7000 series aluminum alloys

The purpose of the present investigation is to determine the relative importance of minor variations in alloy chemistry and thermomechanical treatment on the low cycle fatigue behavior of 7000 series aluminum alloys. Two types of alloying variations are considered: changing the alloy purity level by controlling the iron and silicon content, and changing the grain refiner from chromium to zirconium. The effects of these alloying variations, with regard to mechanical properties other than low cycle fatigue, have been discussed elsewhere.^1-4The purpose of thermomechanical processing is to provide increased strength over 7075-T7351 with equivalent fracture toughness and corrosion properties.^5-7 The effect of the dislocation substructure introduced by thermomechanical processing (TMP) on the high cycle fatigue behavior of 7075 was documented by Reimann and Brisbane.⁸ The present work was undertaken to determine the relative importance of purity level, dispersoid type, and dislocation substructure (TMP) on the low cycle fatigue behavior of 7000 series aluminum alloys. formerly with the Air Force Materials Laboratory, Wright-Patterson AFB, OH     

Forecasting Low-Cycle Fatigue Performance of Twinning-Induced Plasticity Steels: Difficulty and Attempt

We find the existing empirical relations based on monotonic tensile properties and/or hardness cannot satisfactorily predict the low-cycle fatigue (LCF) performance of materials, especially for twinning-induced plasticity (TWIP) steels. Given this, we first identified the different deformation mechanisms under monotonic and cyclic deformation after a comprehensive study of stress–strain behaviors and microstructure evolutions for Fe-Mn-C alloys during tension and LCF, respectively. It is found that the good tensile properties of TWIP steel mainly originate from the large activation of multiple twinning systems, which may be attributed to the grain rotation during tensile deformation; while its LCF performance depends more on the dislocation slip mode, in addition to its strength and plasticity. Based on this, we further investigate the essential relations between microscopic damage mechanism (dislocation–dislocation interaction) and cyclic stress response, and propose a hysteresis loop model based on dislocation annihilation theory, trying to quickly assess the LCF resistance of Fe-Mn-C steels as well as other engineering materials. It is suggested that the hysteresis loop and its evolution can provide significant information on cyclic deformation behavior, e.g., (point) defect multiplication and vacancy aggregation, which may help estimate the LCF properties.     

Fatigue crack propagation of metastable beta titanium-vanadium alloys

The fatigue crack propagation behavior of three titanium-vanadium alloys (24, 28, and 32 wt pct V) which have tensile deformation modes ranging from coarse twinning to wavy and planar slip has been measured in laboratory air and correlated with their low cycle fatigue properties and microstructure. The fatigue crack growth rate of alloys with similar microstructures but different deformation modes, and of alloys with similar deformation modes but different microstructures have been compared. Increasing the deformation barrier mean free path and improving low cycle fatigue properties has been observed to reduce the fatigue crack growth rate at low and inter mediate ΔK levels. The fatigue crack growth data have been compared with that calculated from equations which use microstructure and low cycle fatigue parameters. The predictive capability of these equations which contain only measurable parameters has been found to be quite adequate.     

锆合金变形机理及其板材织构演化规律

锆是核工业的重要结构材料,又是优秀的化工耐蚀结构材料。锆合金的织构会对它的屈服强度、蠕变和疲劳强度、应力腐蚀开裂行为以及辐照尺寸变化等产生很大影响,因此变形机理的研究和织构控制在锆合金的开发利用中有十分重要的地位。综述了锆合金的变形机理,介绍了锆合金板材在不同轧制温度下的织构演化规律,以及退火温度对锆合金板材织构的影响,并总结了织构对锆合金板材力学性能的影响。最后指出,目前对锆合金板材加工后的织构进行精确预测还十分困难,需进行详细深入的研究,同时在加工中产生的织构对加_丁过程的影响以及与温度、应力分布、合金成分和组织的关系还需进一步认识。     

Abnormal Deformation Behavior of Oxygen-Modified <Emphasis Type="Italic">β</Emphasis>-Type Ti-29Nb-13Ta-4.6Zr Alloys for Biomedical Applications

Oxygen was added to the biomedical β-type Ti-29Nb-13Ta-4.6Zr alloy (TNTZ, mass pct) in order to improve its strength, while keeping its Young’s modulus low. Conventionally, with an increase in the oxygen content, an alloy’s tensile strength increases, while its tensile elongation-to-failure decreases. However, an abnormal deformation behavior has been reported in the case of oxygen-modified TNTZ alloys in that their strength increases monotonically while their elongation-to-failure initially decreases and then increases with the increase in the oxygen content. In this study, this abnormal tensile deformation behavior of oxygen-modified TNTZ alloys was investigated systematically. A series of TNTZ-(0.1, 0.3, and 0.7 mass pct)O alloy samples was prepared, treated thermomechanically, and finally solution treated; these samples are denoted as 0.1ST, 0.3ST, and 0.7ST, respectively. The main tensile deformation mechanisms in 0.1ST are a deformation-induced α″-martensitic transformation and {332}〈113〉 mechanical twinning. The large elongation-to-failure of 0.1ST is attributable to multiple deformation mechanisms, including the deformation-induced martensitic transformation and mechanical twinning as well as dislocation glide. In both 0.3ST and 0.7ST, dislocation glide is the predominant deformation mode. 0.7ST shows more homogeneous and extensive dislocation glide along with multiple slip systems and a higher frequency of cross slip. As a result, it exhibits a higher work-hardening rate and greater resistance to local stress concentration, both of which contribute to its elongation-to-failure being greater than that of 0.3ST.     

Low-Cycle Fatigue of Ultra-Fine-Grained Cryomilled 5083 Aluminum Alloy

The cyclic deformation behavior of cryomilled (CM) AA5083 alloys was compared to that of conventional AA5083-H131. The materials studied were a 100 pct CM alloy with a Gaussian grain size average of 315 nm and an alloy created by mixing 85 pct CM powder with 15 pct unmilled powder before consolidation to fabricate a plate with a bimodal grain size distribution with peak averages at 240 nm and 1.8 μm. Although the ultra-fine-grain (UFG) alloys exhibited considerably higher tensile strengths than those of the conventional material, the results from plastic-strain-controlled low-cycle fatigue tests demonstrate that all three materials exhibit identical fatigue lives across a range of plastic strain amplitudes. The CM materials exhibited softening during the first cycle, similar to other alloys produced by conventional powder metallurgy, followed by continual hardening to saturation before failure. The results reported in this study show that fatigue deformation in the CM material is accompanied by slight grain growth, pinning of dislocations at the grain boundaries, and grain rotation to produce macroscopic slip bands that localize strain, creating a single dominant fatigue crack. In contrast, the conventional alloy exhibits a cell structure and more diffuse fatigue damage accumulation.     

Effect of Deformation Temperature on Deformation Mechanism of Fe-6.5Si Alloys with Different Initial Microstructures

Deformation behaviors and mechanisms under different temperatures for columnar-grained Fe-6.5Si(mass%)alloys fabricated by directional solidification and equiaxed-grained Fe-6.5Si alloy fabricated by forging were comparatively investigated.The results showed that,with increasing the deformation temperature from 300 ℃ to500 ℃,the elongation increased from 2.9%to 30.1%for the equiaxed-grained Fe-6.5Si alloy,while from 6.6%to about 51%for the columnar-grained Fe-6.5Si alloy.The deformation mode of equiaxed-grained Fe-6.5Si alloy transferred from nearly negligible plastic deformation to large plastic deformation dominated by dislocation slipping.Comparatively,the deformation mode of the columnar-grained alloy transferred from nearly negligible plastic deformation to plastic deformation dominated by the twining,and finally to plastic deformation dominated by dislocation slipping.Meanwhile,compared with the alloy with equiaxed grains,it was found that ultimate tensile strength and elongation could be increased simultaneously,which was ascribed for the twinning deformation in columnar-grained Fe-6.5Si alloy.This work would assist us to further understand the plastic deformation mechanism of Fe-6.5Si alloy and provide more clues for high-efficiency production of the alloy.     

Texture and anisotropy in the mechanical properties of titanium alloys caused by the mechanism of plastic deformation

Texture formation during sheet stamping and die forging of α titanium alloys is studied, and the effect of texture and the mechanism of plastic deformation on the strength of internal-pressure spherical vessels is considered. It is shown that, apart from texture, the anisotropy of the strength properties of the α alloys, which is estimated from the difference in the uniaxial-and biaxial-loading strengths, also depends on the chemical composition of the alloy. In the textureless state, the strength of the spherical vessels is higher than the uniaxial strengths of the VT5-1kt, PT3V, and PT3Vkt alloys by 4, 16, and 38%, respectively. This effect is found to be caused by the difference in the relative values of the critical shear stresses for operating slip and twinning systems. The high ductility of the PT3Vkt alloy is related to the fact that it has a ratio of critical shear stresses in the operating slip and twinning systems such that the material is virtually isotropic with respect to tensile loads. This specific feature minimizes the effect of the incompatibility of deformation in grains with different orientations during tension, which is the main cause of the fracture of titanium alloys. The results obtained are used to propose a quantitative criterion to estimate the technological ductility in order to design new titanium alloys.     

Low-Cycle fatigue of dispersion-strengthened copper

The cyclic deformation behavior of a dispersion-strengthened copper alloy, GlidCop Al-15, has been studied at plastic strain amplitudes in the range 0.1 pct ≤Δε _p/2 ≤ 0.8 pct. Compared to pure polycrystalline copper, the dispersion-strengthened material exhibits a relatively stable cyclic response as a consequence of the dislocation substructures inherited from prior processing and stabilized by the A1₂O₃ particles. These dislocation structures remain largely unaltered during the course of deformation; hence, they do not reveal any of the features classically associated with copper tested in fatigue. At low amplitudes, the fatigue lifetimes of the dispersion-strengthened copper and the base alloy are similar; however, the former is more susceptible to cracking at stress concentrations because of its substantially greater strength. This similarity in fatigue lifetimes is a consequence of the dispersal of both deformation and damage accumulation by the fine grain size and dislocation/particle interactions in the GlidCop alloy. The operation of these mechanisms is reflected in the fine surface slip markings and rough fracture surface features for this material. Formerly Graduate Research Assistant, University of California, Davis, CA