超低碳铜时效强化钢的热稳定性

研究了400℃至800℃再加热处理后超低碳铜时效强化钢组织和性能的变化.利用光学显微镜、扫描电镜、透射电镜观察和X射线衍射分析了不同温度再加热处理后钢显微组织和ε-Cu沉淀的特征.结果表明,再加热温度不高于650℃的条件下,钢的强度和韧性未明显下降,即具有优良的热稳定性；再加热温度高于650℃则钢的屈服强度明显降低,这是由于基体组织发生明显的回复以及ε-Cu沉淀粗化；再加热温度高于700℃钢的韧性明显降低,这是大量高硬度M/A岛组织出现所造成.分析表明基体组织的回复,ε-Cu沉淀的数量和尺寸及M/A岛组织是影响超低碳铜时效强化钢热稳定性的主要因素.     

First differential of temperature dependent ultrasonic parameters as an effective tool for identifying precipitation reactions in a slow heat-treated 8090 Al–Li alloy

Ultrasonic velocities and attenuation measurements have been carried out to characterise the fine scale precipitation events in a slow heat-treated 8090 Al–Li alloy. The alloy was subjected to a slow heating (at the rate of 10 K h⁻¹) to the temperature of 463 K, before and after solution annealing at 803 K for 1 h. The changes in bulk modulus, Young's modulus and Poisson's ratio have been obtained from the ultrasonic velocity data. The variation in hardness and density has been found to be consistent with the changes in velocities and elastic constant. The ultrasonic on-line measurements from 300 to 623 K reveal clearly all the four transitions, including the formation of GP zones at 368 K, formation of δ′ at 470 K, dissolution of δ′ at 532 K and the formation of equilibrium S′ and δ phases at 590 K. The first differential of temperature dependent ultrasonic parameters is found to be particularly effective in clearly diagnosing all the fine scale precipitation/dissolution events. Differentiation between the precipitation and dissolution type reactions is also possible from careful analysis of the first differential plots.     

Voltametry and EQCM study of copper oxidation in acidic solution in presence of chloride ions

Cyclic voltametry experiments coupled with electrochemical quartz crystal microbalance (EQCM) measurements showed the corrosion mechanism of electrodeposited copper in presence of chloride ions. The oxidation of copper in acidic solution containing high concentration of Cl⁻ begins with formation of Cu⁺ ions. The Cu⁺ concentration at the vicinity of the electrode increasing, the small solubility product of CuCl is then exceeded, leading to a CuCl precipitation on the gold covered quartz crystal used as working electrode. For highest anodic potentials, the oxidation of electrodeposited copper or CuCl precipitate phases could occur. A combination with structural techniques like SEM, EDAX, AFM and DRX gives insight into the morphology and the nature of these CuCl precipitates.     

Localized corrosion mechanism associated with precipitates containing Mg in Al alloys

To clarify the localized corrosion mechanism associated with precipitates containing Mg in Al alloys, the simulated bulk precipitates of S and β were synthesized through melting and casting. Their electrochemical behaviors and coupling behaviors with α（Al） in NaCl solution were measured. Meanwhile, simulated Al alloys containing S and β particles were prepared and their corrosion morphologies were observed. It＇s found that there exist two kinds of corrosion mechanisms associated with precipitates containing Mg. The precipitate of β is anodic to the alloy base, resulting in its anodic dissolution and corrosion during the whole corrosion process. While, there exists a corrosion conversion mechanism associated with the S precipitate, which contains active element Mg and noble element Cu simultaneously. At an initial stage, S is anodic to the alloy matrix at its periphery and the corrosion occurs on its surface. However, during its corrosion process, Mg is preferentially dissolved and noble Cu is enriched in the remnants. This makes S become cathodic to a（Al） and leads to anodic dissolution and corrosion on the alloy base at its periphery at a later stage.     

InconelX-750高温合金的组织变化

为了监控航空发动机热端气体通道的温度，用定量金相法测定了冷变形InconelX-750高温合金丝材晶粒尺寸随热处理温度的变化。研究发现，在871℃热处理，合金发生完全再结晶，在982℃以上，晶粒尺寸随热处理温度的升高而长大。合金中的析出相主要有γ＇、Cr23C6和（Ti，Nb）C。     

T23钢再热裂纹敏感性的改善及其组织

 T23钢较高的再热裂纹敏感性严重危害了超超临界火电厂的安全运行。为了改进T23钢再热裂纹敏感性,主要通过改变其碳、钨等元素的质量分数,并且采用Gleeble热模拟及等温缓慢拉伸方法评判T23钢和改进型T23钢焊接热影响区粗晶区(CGHAZ)的再热裂纹敏感性。利用光学显微镜(OM)、扫描电镜(SEM)和透射电镜(TEM)研究两者CGHAZ的微观组织,探讨了微观组织对改进型T23钢再热裂纹敏感性的影响。结果表明,改进型T23钢的再热裂纹敏感性得到极大的改善,且其常规力学性能均达到ASME规范要求。与T23钢相比,改进型T23钢CGHAZ晶界M₂₃C₆相和晶内MX相数量均较少,同时,其固溶强化元素碳、钨质量分数较低。因此,改进型T23钢CGHAZ晶内晶界的强度差降低,再热裂纹敏感性改善。另外,较小的CGHAZ晶粒尺寸及较少的M-A组元也有助于降低改进型T23钢的再热裂纹敏感性。改进型T23钢晶界较少的M₂₃C₆相还使得晶界上孔洞连接和裂纹扩展的速率降低。设计的改进型T23钢成分可以为以后进一步改善T23钢再热裂纹敏感性提供参考。     

Gadolinium solubility and precipitate identification in Mg-Gd binary alloy

Gadolinium (Gd) solubility in magnesium (Mg) matrix and precipitate composition in Mg-Gd binary alloys were investigated. The alloys containing different Gd contents (10wt.%-35wt.%) were employed to identify Gd solubility after annealing at different temperatures. It was confirmed that the maximum Gd solubility was 22.8wt.% at 550℃ based on the regression analysis method. Mg5+xGd (0precipitates coexisted in all investigated alloys owing to the strong component segregation during solidification. The fraction of Mg5+xGd(0precipitate could not be eliminated even when being annealed at 550℃. This thermal stable precipitate played a significant role in mechanical properties. Therefore, it is very necessary to consider the effect of Mg3Gd precipitate on properties of Mg-Gd based alloys in future.     

A comparison of three weld consumables for P92 under creep

Abstract

To encourage realistic power plant weld heat-affected zone failures within reasonable test times in laboratory creep testing, a welding consumable for P92 steel with the best creep performance was sought, to avoid failures in the weld metal itself. Therefore, a short term creep test programme was undertaken to evaluate weld pads manufactured using three commercially available consumables for P92, the results of which are presented in this paper. The effects of weld consumable composition are discussed both in general and with specific reference to the behaviour observed. The best overall and the poorest performing weld consumables were identified by composition. Microstructural investigations revealed the presence of precipitate free zones, that more readily formed using the poorest performing consumable as the result of retained δ–ferrite, since its deposited chemical composition led to the lowest value of δ–ferrite formation temperature. A consumable not based on P92 but on the stronger steel alloy FB2 did not perform as well as expected, confirming previous suggestions that the compositional factors which make a parent material creep-strong do not apply on a one-to-one basis to weld metals.     

含氟体系中重铀酸铵沉淀过程的研究

应用ＵＦ６水解模拟液ＵＦ２Ｏ２＋４ＨＦ与ＮＨ３水反应研究了ＡＤＵ的沉淀过程，研究结果认为，ＡＤＵ的沉淀过程可分为：中和阶段、ＡＵＦ［（ＮＨ４）３ＵＯ２Ｆ５］生成阶段、ＡＤＵ生成阶段。并对中间化合物ＡＵＦ结晶生成规律，化学组成等进行了研究。详细讨论了一些重要工艺条件对ＡＤＵ生成条件及特性的影响。     

山葡萄酒浑浊的控制措施

山葡萄酒浑浊的主要原因有酵母菌自溶、微生物污染、氧化过度、蛋白质和酒石酸盐过多等。生产中常采取的控制措施有添加果胶酶、及时分离酒脚、严格下胶、冷处理、防止微生物污染、做好原料的分选工作等。