Relations of Microstructural Attributes and Strength-Ductility of Zirconium Alloys with Hydrides

As the first safety barrier of nuclear reactors,zirconium alloy cladding tubes have attracted extensive attention because of its good mechanical properties.The strength and ductility of zirconium alloy are of great significance to the service process of cladding tubes,while brittle hydrides precipitate and thus deteriorate the overall performance.Based on the cohesive finite element method,the effects of cohesive strength,interfacial characteristics,and hydrides geometric characteristics on the strength and ductility of two-phase material(zirconium alloy with hydrides)are numerically simulated.The results show that the fracture behavior is significantly affected by the cohesive strength and that the overall strength and ductility are sensitive to the cohesive strength of the zirconium alloy.Furthermore,the interface is revealed to have prominent effects on the overall fracture behavior.When the cohesive strength and fracture energy of the interface are higher than those of the hydride phase,fracture initiates in the hydrides,which is consistent with the experimental phenomena.In addition,it is found that the number density and arrangement of hydrides play important roles in the overall strength and ductility.Our simulation provides theoretical support for the performance analysis of hydrogenated zirconium alloys during nuclear reactor operation.

Effects of trace element and purification on properties of AZ80 magnesium alloy

The effects of trace element Fe on the corrosion behavior of AZ80 magnesium alloy were investigated by salt spray test and electrochemical measurements.The results show that the corrosion rate decreases with decreasing the trace element Fe content in an approximately linear relation even though the amount of trace element Fe reduces to 0.000 2%(mass fraction).The electrochemical measurements show that the corrosion potential(φcorr)of the alloy with lower trace element Fe content shifts to less negative value.It is suggested that the control trace element by purification is an effective way to enhance the corrosion resistance of AZ80 magnesium alloy.

Influence of Trace Alloying Elements on Corrosive Resistance of Cast Stainless Steel

The influences of trace alloying elements niobium, vanadium and zirconium on the corrosive resistance of 18 8 type cast stainless steel have been studied in detail by orthogonal design experiments. The results show that zirconium is mainly in the form of compound inclusions, which is unfavorable to promote the corrosive resistance of the cast stainless steel. It can alleviate the disadvantageous influence of carbon addition on corrosive resistance when some elements such as vanadium and niobium exist in the steel, and niobium has a remarkable influence on the intergranular corrosive resistance but unobvious on the pitting corrosion, and vanadium has a slightly favorable influence on the corrosive resistance of the steel.

EFFECT OF TRACE ELEMENTS WITH ZERO SELF－INTERACTIONCOEFFICIENT ON CRYSTALLIZATION TEMPERATUREOF IRON CARBON ALLOYS

The effect of trace elements with zero self-interaction coefficient on crystallization temperature of iron carbon alloys was studied and the mathematic equation was developed based on thermodynamics in the present researeh. With the equation developed in this paper, the effects of nitrogen on crystallization temperature of Fe-3.45C-2.15Si0. 16Mn and Fe-3.45C-2. 15Si-0. 80Mn alloys were discussed.

OUT-OF-PILE CORROSION RESISTANCE OF NEW ZIRCONIUM ALLOYS IN 500 ℃/10 3MPa STEAM

he out of pile corrosion resistance of new Zirconium alloys in 500℃/10 3MPa steam has been investigated and the effect of alloying elements, Sn,Nb,Fe,Cr on the property has been analyzed. The results show that the new alloys have better corrosion resistance than Zircaloy 4. That no nodular corrosion is found during test cycles shows the nodular corrosion resistance can be dramatically improved by addition of alloying elements Nb. The Fe/Cr ratio should be properly controlled if there is Cr addition in the alloys when developing new alloys.

电感耦合等离子体原子发射光谱法测定锆合金中5种元素的含量

提出了电感耦合等离子体原子发射光谱法测定锆合金中锡、铌、铁、铬、镍含量的方法。取样品0.1 g,加入5 mL水、5 mL硝酸和0.5 mL氢氟酸,于100℃加热5 min,用水定容至25 mL。设置仪器射频功率为1300 W,雾化气流量为0.80 L·min^(-1),进样量为2.0 mL·min^(-1),测定5种元素在Sn 242.949 nm、Nb 309.418 nm、Fe 259.941 nm、Ni 221.648 nm、Cr 267.716 nm等分析谱线处的响应强度,基质匹配法定量。结果表明:锡、铌的质量浓度在150μg·mL^(-1)以内,铁、铬、镍的质量浓度在15μg·mL^(-1)以内分别与对应的响应强度呈线性关系;锡检出限(3s)为16μg·g^(-1),其他元素检出限(3s)均低于3.0μg·g^(-1);各元素方法重复性的相对标准偏差(n=10)均小于2.0%,加标回收率为99.0%~109%;采用锆合金标准物质SRM360b进行验证,测定值均在认定值的不确定度范围内。

Corrosion behavior of Zr–Nb–Cr cladding alloys

Zr-Nb-Cr alloys were used to evaluate the effects of alloying elements Nb and Cr on corrosion behavior of zirconium alloys. The microstructures of both Zr substrates and oxide films formed on zirconium alloys were characterized. Corrosion tests reveal that the corro- sion resistance of ZrxNb0.1Cr （x = 0.2, 0.5, 0.8, 1.1; wt%） alloys is first improved and then decreased with the increase of the Nb content. The best corrosion resistance can be obtained when the Nb concentration in the Zr matrix is nearly at the equilibrium solution, which is closely responsible for the formation of columnar oxide grains with protective characteristics. The Cr addition degrades the corrosion resistance of the Zrl.lNb alloy, which is ascribed to Zr（Cr,Fe,Nb）2 precipitates with a much larger size than β-Nb.

Effect of Cd and Sn Addition on the Microstructure and Mechanical Properties of AI-Si-Cu-Mg Cast Alloy

The present work has investigated the effect of trace elements Cd and Sn on the microstructure and mechanical properties of Al-Si-Cu-Mg cast alloy. With the increase of Cd addition the strength of alloy rises at first and then drops. The optimal amount of Cd and Sn addition for Al-Si-Cu-Mg alloy is about 0.27% and 0.1% respectively. Due to the formation of some coarse Cd-rich phases and pure Cd particles the mechanical properties of alloy decrease when Cd amount exceeds 0.27%. When more than 0.1% Sn added, some Sn atoms form low-melting eutectic compound at grain boundary, and then cause over-burning in alloy when solution treated, which may deteriorate properties of alloy, especially ductility of alloy. On the other hand, the addition of Cd and Sn remarkably increases the peak hardness and reduces the time to reach aging peak in Al-Si-Cu-Mg alloy. The action of Cd /Sn in quaternary Al-Si-Cu-Mg alloy is effectively the same as that occur in binary Al-Cu alloy that the enhanced hardening associated with Cd / Sn addition is due to the promotion of the 6’ phase.

有限元分析不同材料对超短种植体的影响

目的 应用有限元分析研究不同种植材料对超短种植体及周围骨的应力影响效果,旨在为超短种植体修复下颌第一磨牙的应用奠定理论基础。方法 通过SoildWorks软件建立下颌骨模型和三种不同材质的一段式超短种植体模型,三种材质分别为氧化锆(ZrO)、钛锆合金(Ti-Zr)、碳纤维加强型聚醚醚酮(carbon fiber reinforced polyether ether ketone, CFR-PEEK)。采用ABAQUS有限元软件模拟咬合力对每个模型施加轴向以及斜向载荷,运算并分析种植体及周围骨的应力分布情况。结果 CFR-PEEK组种植体以及皮质骨的Von-Mises应力值低于Ti-Zr组和ZrO组。结论 采用超短种植体修复骨量不足的下颌第一磨牙区,从生物力学角度分析采用CFR-PEEK比Ti-Zr和ZrO更有优势。

微量元素La和Al-5Ti-1B复合细化Al-Cu机理

实验研究了复合添加微量元素La和Al-5Ti-1B对Al-Cu合金凝固组织的影响,发现与单独添加Al-5Ti-1B相比,复合添加Al-5Ti-1B和微量La可进一步细化Al-Cu合金凝固组织,降低α-Al的形核过冷度.结合高分辨透射电镜表征和理论计算,探明了复合添加微量元素La和Al-5Ti-1B对Al-Cu合金凝固组织的细化机理:经Al-5Ti-1B细化处理的Al-Cu合金凝固时,Cu富集于α-Al与TiB_(2)粒子的界面处,增加了α-Al与TiB_(2)粒子间的错配度,降低了TiB_(2)粒子对α-Al的异质形核能力;添加微量的La能有效降低α-Al与TiB_(2)粒子间的错配度,减小TiB_(2)粒子和α-Al间的界面能及接触角,从而提高TiB_(2)粒子促进α-Al的异质形核能力和Al-5Ti-1B对Al-Cu合金晶粒的细化效果.

高分辨电感耦合等离子体质谱法测定镍基高温合金中的痕量元素

本研究建立了高分辨电感耦合等离子体质谱(HR-ICP-MS)法测定镍基高温合金中痕量元素。采用盐酸、硝酸和氢氟酸溶解镍基高温合金样品,根据待测元素同位素丰度大、干扰小、灵敏度高的原则,优化各待测元素的同位素和分辨率,有效消除了绝大多数多原子和双电荷离子的干扰。另外,考察了基体、合金成分和溶样酸对待测痕量元素的质谱干扰,通过选取合适的内标133Cs,可以克服基体效应并降低信号漂移。利用甲基异丁基酮萃取Cd,萃取效率达99.7%,消除了镍基高温合金中主成分Mo的质谱干扰。各痕量元素校准曲线的线性相关系数均大于0.999,方法检出限为0.0021~0.074μg/g。用本方法分析镍基高温合金成分分析标准物质中的痕量元素含量,测定结果的相对标准偏差(RSD,n=6)在2.9%~7.8%之间,测定值与标准值非常接近。该方法前处理简单、分析速度快、结果准确可靠,能够满足镍基高温合金中痕量元素的检测需求。

运用ICP-MS测定高温合金中的As、Pb、Sn、Bi、Sb、Hg、Cd痕量元素

采用HNO3、HCl低温加热方式溶解高温合金,直接以电感耦合等离子体质谱法(ICP-MS)测定0.0001~0.0500%的As、Pb、Sn、Bi、Sb、Hg、Cd。考察了仪器的优化条件选择,酸度及内标元素选择。试验结果表明:高温合金中待测杂质元素溶解完全,空白低,加入内标Sc和Rh改善了测定时的精密度和稳定性,消除了各基体产生的基体效应,检测下限0.019~0.080μg/mL,,相关系数r0.999,回收率92.8%~109.4%,RSD<5%,方法可满足同时测定高温合金中7种痕量杂质元素的需要。

Mg/Si比对Al⁃Mg⁃Si⁃Zn合金自然时效效应的影响

通过显微硬度测试、导电率测试、差示扫描量热分析和透射电子显微镜,探究了两种不同Mg/Si比的Al⁃Mg⁃Si⁃Zn合金中自然时效对后续180℃人工时效的影响。结果表明,在富Si合金中,自然时效对后续人工时效的峰值硬度没有明显的负面效应,而富Mg合金则表现出显著的自然时效负面效应。虽然有少量板条相存在,针状的β″相为两种合金在所有峰值时效状态下的主要析出强化相。富Mg合金的自然时效负面效应主要与β″相尺寸粗化和析出相体积分数减小有关。不同Mg/Si比的Al⁃Mg⁃Si⁃Zn合金中自然时效团簇的特性具有显著差异。富Mg合金中的自然时效团簇有相当一部分在人工时效时是稳定的,同时稳定的团簇大部分不能作为析出相的形核点,导致析出相的形核点数量减少,析出相尺寸粗化。而大量富Si合金中的自然时效团簇在后续人工时效早期发生溶解,来自溶解团簇的溶质原子重新用于β″相的形核生长,因此析出相尺寸粗化不明显。

电感耦合等离子体质谱法测定镁合金中的痕量元素

采用操作简单的基体匹配法和内标法校正基体,建立了一套完整的电感耦合等离子体质谱(ICP-MS)法检测镁合金中的铜、钴、银、铅、锑、铍、铬、铟、钇、镉、锰、钛、钽、镧、铈15种痕量元素.检出限、加标回收、精密度的相关试验表明,各元素的检出限范围为0.0039~1.6µg/L,加标回收率为95.1%~109.2%,精密度为0.2%~2.3%.方法简单、快速、高效,可满足市场上对镁合金中痕量元素的检测需求.

合金元素对铬锆铜综合性能的影响研究

阐述了常见添加微合金元素对铬锆铜体系性能的改善作用,找出较优的微合金体系方向以得到最佳综合性能,并通过对比分析,提出了当前研究存在的问题,对未来铬锆铜材料工艺方向的发展进行了思考。

核级海绵锆对Zr-4铸锭铁元素的影响

本文针对核级海绵锆中氯、铁元素含量对锆合金铸锭中铁元素含量的影响规律进行分析,通过对熔炼后的黑色挥发物及最终铸锭化学检测分析,发现海绵锆中氯、铁元素含量较高会增加锆合金铸锭中铁元素含量的控制难度。为今后锆合金铸锭铁元素含量的控制提供了原材料质量方面控制参考,也为核级海绵锆氯、铁元素含量的控制的重要性提供了依据。

微量元素磷在铁镍基变形高温合金中的作用

综述了磷对铁镍基变形合金的影响及机理。简述了磷的性质 ,来源及冶炼控制。介绍了磷的凝固偏析及对合金凝固过程的影响与机理。以微量元素对晶界能、晶界扩散和晶界结合力的影响机理为基础 ,比较并分析了磷对合金组织结构和力学性能的各种影响机制。

添加微量元素对Cu-Ni-Si合金性能的影响

分析了微量元素在改善Cu-Ni-Si合金强度同时又影响导电性的机理,综述了Zn、Cr、P、Al等微量元素对Cu-Ni-Si合金硬度、导电率等的影响规律,表明利用合金化规律在Cu-Ni-Si合金中添加不同的微量元素可以得到强度和导电率匹配良好的超高强度Cu-Ni-Si合金。

微量元素对高强铝合金焊缝组织和力学性能的影响

在ER2319焊丝的基础上,分别添加少量Ce、Cr及Mn元素制备了3种焊丝。采用光学显微镜、扫描电镜和能谱分析技术研究微量元素Ce、Cr和Mn对MIG焊缝组织和性能的影响。结果表明:Ce能够细化二次枝晶间距,但Ce易与Ti、Zr相互反应在晶界生成块状硬而脆的AlCuCeTiZrV复杂金属间化合物,降低了Ti和Zr的异质形核作用,使焊缝组织成柱态。而Cr和Mn则能促进Al3Ti、Al3Zr以及复合析出物Al3(Zr,Ti)的析出,增加这些颗粒在高温条件下的稳定性,能够显著细化焊缝晶粒和晶界共晶相,提升接头的力学性能。但Mn的含量达到0.58%时,焊缝中心容易形成粗大树枝晶。

添加合金元素Cu和Mn对锆合金中第二相的影响

以Zr-4为母合金,分别添加电解纯铜或电解金属锰,用非自耗真空电弧炉熔炼了成分不同的6种锆合金.用透射电子显微镜观察了合金中第二相的形貌,用EDS分析了第二相的成分,用SAD确定了第二相的晶体结构.添加Cu元素的合金中有3种第二相:Zr(Fe,Cr)2粒子、Zr(Fe,Cr,Cu)2粒子和含少量Fe或不含Fe的Zr2Cu粒子;添加Mn元素的合金中只有1种Zr(Fe,Cr,Mn)2第二相,且随着合金中Mn的质量分数从0.07%增加到0.35%,Zr(Fe,Cr,Mn)2粒子中Mn元素的质量分数也升高.