Stability of the solid solution of scandium in aluminum

In recent years scandium has attracted the attention of researchers as an alloying component of aluminum alloys. Industrial compositions of scandium-alloyed aluminum alloys have been developed with consideration of its various positive effects on the structure and properties of aluminum. The results of an investigation of the kinetics of decomposition of a solid solution of scandium in aluminum are analyzed and generalized. C-curves of the decomposition are presented for aluminum alloys with different contents of Sc, Si, Fe, Mn, Zn. Translated from Metallovedenie i Termicheskaya Obrabotka Metallov, No. 2, pp. 15–20, February, 1997.     

Effect of aluminum content on the decomposition kinetics of supersaturated solid solution in Mg-Al-alloys

A. A. Baikov Institute, of Metallurgy, Moscow. Translated from Metallovedenie i Termicheskaya Obrabotka Metallov, No. 4, pp. 28–32, April, 1989.     

On the possibility of scandium alloying of copper-containing aluminum alloys

Scandium alloying of aluminum alloys can substantially improve their operating properties and weld-ability. Commercially scandium-alloyed alloys have been developed for the Al - Mg, Al - Zn - Mg, and Al - Mg - Li systems. The scandium alloying of aluminum alloys containing copper as an alloying component should be performed carefully, because scandium can produce a chemical compound with copper. This worsens the strength properties of preforms and decreases their plasticity and fracture toughness due to the increased volume fraction of the excess phases. In this work, conditions for scandium alloying are determined for the copper-containing alloys D16 and 1933.Translated from Metallovedenie i Termicheskaya Obrabotka Metallov, No. 2, pp. 23 – 27, February, 1995.     

Solute strengthening from first principles and application to aluminum alloys

Alloys containing substitutional solutes exhibit strengthening due to favorable solute fluctuations within the alloy that hinder dislocation motion. Here, a quantitative, parameter-free model to predict the flow stress as a function of temperature and strain rate of such alloys is presented. The model builds on analytic concepts developed by Labusch but introduces key innovations rectifying shortcomings of previous models. To accurately describe the solute/dislocation interaction energies in and around the dislocation core, density functional theory and a flexible-boundary-condition method are used. The model then predicts the zero temperature flow stress, the energy barrier for dislocation motion, and thus the finite temperature flow stresses. The model is used to predict the flow stresses of various Al alloys. Excellent results are obtained for Al–Mg and Al–Mn. Al–Fe with ppm levels of Fe is not predicted well but, using experimental results for Fe, results for the quasi-binary Al–Cr–(Fe) and Al–Cu–(Fe) alloys agree well with experiments. The model is also consistent with the “stress equivalency” postulate of Basinski. This parameter-free model using first-principles input thus provides a basis for achieving the long-sought goal of computational design of alloys, within the context of solute-strengthening mechanisms.     

Effect of scandium on superplasticity of Al-Mg alloys

1　ＩＮＴＲＯＤＵＣＴＩＯＮＡｌ Ｍｇ Ｓｃａｌｌｏｙ ｐｏｓｓｅｓｓｅｓｈｉｇｈｓｔｒｅｎｇｔｈ ,ｈｉｇｈｔｏｕｇｈｎｅｓｓ,ｌｏｗｅｒｄｅｎｓｉｔｙ,ｇｏｏｄｗｅｌｄａｂｉｌｉｔｙａｎｄｃｏｒ ｒｏｓｉｏｎｒｅｓｉｓｔａｎｃｅ[1 ,2 ] .Ａｐｐｌｙｉｎｇｔｈｅｓｕｐｅｒｐｌａｓｔｉｃｉｔｙｏｆｔｈｅｓｅａｌｌｏｙｓｔｏｆｏｒｍｉｍｐｏｒｔａｎｔｃｏｍｐｌｅｘｐａｒｔｓｆｏｒｔｈｅｓｐａｃｅｃｒａｆｔｉｓａｓｉｇｎｉｆｉｃａｎｔｒｅｓｅａｒｃｈｓｕｂｊｅｃｔａｔｐｒｅ ｓｅｎｔ[3 ,4] .Ｔｈｉｓｒｅｓｅａ…     

Effect of large cold deformation after solution treatment on precipitation characteristic and deformation strengthening of 2024 and 7A04 aluminum alloys

1Introduction Studies on thermomechanical treatment of aluminum alloy can date from the1960s[1,2].A great deal of achievements concerning this study has been obtained after near40years of development[3?7].Among them,the achievement of intermediate thermom…     

Effect of high-temperature decomposition of the solid solution on the low-cycle fatigue resistance of semifinished products made of aluminum alloy 1163

The surface of anodized parts made of 1163T aluminum alloy that are produced by mechanical treatment of large pressed or rolled semifinished products exhibits dark regions. These regions have a higher electrical conductivity 7 than the rest of the anodized surface, colored light-yellow. Some authors explain the appearance of me dark stains by high-temperature decomposition of the solid solution, which is initiated by secondary heating of these surface regions due to the heat of surrounding volumes in random interruptions of the cooling process. The aim of the present work is to refine the dependence of on the endurance in tests for low-cycle fatigue of specimens from seminifinished products made of 1163 alloy in order to establish the intensity of the decrease of the endurance and the admissible increase of in the region of dark stains.Translated from Metallovedenie i Termicheskaya Obrabotka Metallov, No. 6, pp. 16–19 June, 1995.     

Zr元素含量对钛基钎料合金固溶强化的影响

利用EET理论分析Zr元素对钛基钎料合金的固溶强化效果,得出锆含量自45%~12%变化时,Ti-Zr-15Cu-10Ni(质量分数,%)钎料合金晶胞内最大共价电子数先保持不变、而后减小再增大.当锆含量为37.5%时,Zr元素对钛基钎料合金的固溶强化作用相对较大,采用此锆含量的钎料合金Ti-37.5Zr-15Cu-10Ni(质量分数,%)对Ti₃Al-Nb合金进行同质过渡液相扩散连接.在连接温度低于1000℃条件下,钎料合金的扩散能力主要受保温时间的影响;在较高连接温度下,钎料合金的扩散能力明显提高,可在短时保温条件下形成组织均匀、无析出物的连接界面.     

Progress in the strengthening of aluminum alloys by heat treatment

This article examines progress recently made in the strengthening of aluminum alloys by heat treatment. The treatment maximizes strength while leaving the alloy with relatively high corrosion resistance.VILS. Translated from Metallovedenie i Termicheskaya Obrabotka Metallov, No. 11, pp. 30–35, November, 1994.     

Effect of scandium on the hot extrudability of 7075 aluminum alloy

This study investigated the effect of the addition of scandium on the hot extrudability of 7075 alloys. Three kinds of Al-Zn-Mg-(Sc) alloys with up to 0.30 wt.% Sc were prepared, including 7075 aluminum alloy without Sc (AA7075). Differential scanning calorimetry (DSC) analyses and hot compression tests were conducted to examine the incipient melting temperature of the alloys produced. The addition of 0.30 wt.% Sc resulted in significant grain refinement and a fully equiaxed microstructure. Hot compression tests were conducted to determine the critical damage values based on Cockroft-Latham criterion. Then, the surface quality of an extruded bar of each alloy was simulated with a finite element code. The surface condition of an extruded bar was predicted and compared with the experimental results. After hot extrusion, AA7075 without the addition of Sc showed a more moderate surface quality than the alloys modified with Sc. However, AA7075 revealed coarse-grained bands just below the surface area. Extrusion limit diagrams were constructed for the three alloys.     

含锆铝合金的力学性能和强化机理

研究了高强铝合金的力学性能与Zr含量的关系，计算了合金的各种强化因素值。研究发现：合金的抗拉强度巩和屈服强度如σ0.2均随Zr含量的增加而增大，增幅分别达到11．8％和12．6％；合金延伸率δ在Zr添加量不高时随Zr含量的增加而增大，在Zr含量为0．06％时出现峰值，随后合金延伸率δ逐渐稳定在8％左右。结合合金显微特征，合金强化机理主要包括晶粒细化、颗粒弥散强化及形变强化，在Zr含量为0．16％的合金中相应的强化值分别为21.35和14MPa.     

高强Al-Ni系铸造铝合金的挤压铸造及强化机制

为了开发新的高强铸造铝合金材料,分别采用3种铸造工艺,砂型铸造、金属型铸造和挤压铸造,制备了一种以Al-Ni共晶体系为基础的AlZn6Ni4Mg2Cu铸造铝合金材料。研究了Ni元素、热处理和铸造工艺对其微观组织、力学性能的影响规律,揭示了其强化机制。结果表明:4%(质量分数)的Ni在该铝合金中形成了大量的共晶组织(α-Al+Al_3Ni),同时改善其力学性能和铸造性能,起到了共晶强化的作用;固溶和时效热处理导致Al_3Ni相的球化和MgZn_2相的时效析出,提高了该铝合金的强度;相比砂型铸造和金属型铸造,挤压铸造时该铝合金的晶粒和Al3Ni相最细小,力学性能最佳,抗拉强度为586 MPa,断后伸长率为3.5%。由此得出:AlZn6Ni4Mg2Cu铸造铝合金的强化机制为η(MgZn_2)相的时效强化和Al_3Ni相的弥散强化,挤压铸造加T6热处理后,该铝合金的力学性能达到最佳值。     

固溶时间对7003铝合金显微组织与性能的影响

用显微硬度计、电子拉伸试验机、扫描电子显微镜(SEM)、能谱(EDS)等手段,对不同时间固溶处理的7003铝合金时效前后的显微组织与性能进行了研究.结果表明,随着固溶时间的延长,第二相先溶解后又有新的析出并长大,第二相的强化效果先是降低后又增强,从而其强度和硬度先降低后增强;时效后的强度和硬度明显高于时效前,且743 K×70 min固溶的合金经过393 K×50h时效后,其硬度、抗拉强度、屈服强度和伸长率分别达到118 HV0.1、347.0 MPa、286.1 MPa和15.5%.     

Mg/Si比对6000系铝合金自然时效和析出强化的影响

采用硬度测试、差示扫描量热法(DSC)分析及透射电镜(TEM)表征手段,观察并研究了Mg/Si比对6000系Al-Mg-Si合金自然时效及烘烤硬化性能的影响。结果表明:合金在自然时效过程的硬化速率与Mg/Si比关系不大,过剩Si合金在自然时效阶段硬度较高,不利于其成形,而该合金较高的析出动力学使其人工时效后具有足够的强度;合金经过自然时效后会使析出相粗化,密度减小,导致合金的时效强度明显降低,自然时效对过剩Mg合金的危害作用更大,这可能与其自然时效过程中形成的富含Mg的原子团簇难以转化为β″有关。