New Magnesium Composite with Mg17Al12 Intermetallic Particles

Powder Metallurgy and Metal Ceramics - Although magnesium is one of the materials with the lowest density, its application is limited amongst other commercial materials due to insufficient...     

Effect of Pb Addition on the Discontinuous and Continuous Mg17Al12-β Precipitate During Solidification of AZ91 Magnesium Alloy

The purpose of this study is to investigate the effect of varying Pb additions on the precipitation sequence of the as-cast and aged AZ91 alloy. The amount of discontinuous precipitate gets reduced by increasing the Pb addition. The phase fraction of as-cast and aged alloys demonstrates that by Pb addition Mg₁₇Al₁₂ phase is reduced to 37.7 and 38.7 % respectively.     

Effect of Precipitate Shape and Habit on Mechanical Asymmetry in Magnesium Alloys

Asymmetric yield behavior in tension and compression is a common and usually undesirable feature of wrought magnesium alloys. To prevent yield asymmetry, it is necessary to favor slip over twinning, as it is the unidirectional nature of twinning combined with the strong textures produced in wrought magnesium alloys that produce yield asymmetry. In this article, the potential to use precipitates to strengthen selectively against twin growth is discussed. The effect of precipitate's shape and habit on strengthening of slip and twinning is calculated using simple Orowan-based models. It is shown that basal plate precipitates, although being poor strengtheners against basal slip, are good strengtheners against twin growth. This is because they produce the maximum unrelaxed back-stress when they remain unsheared inside the twin. The predictions of the model have been validated against experiments for two alloys that form different precipitate types: AZ91 (basal plates). and Z5 (c-axis rods). Crystal plasticity modeling has been used to predict that an optimized distribution of basal plate precipitates is expected to strongly reduce yield asymmetry, even in strongly textured magnesium alloy.     

Relationship Between Work Hardening Capacity and Compressive Creep Behavior in a Hot-Extruded Mg–6Al–1Zn Alloy Rod

Metallurgical and Materials Transactions A - This work investigated the compressive creep behavior of a hot-extruded Mg–6Al–1Zn alloy rod in relation to its work hardening capacity. The...     

钴基高温合金GH188中镧化物类型及元素Mg晶界偏聚的研究

使用俄歇电子谱仪（ＡＥＳ）、透射电镜结合能谱仪（ＥＤＡＸ）及扫描电镜等分析仪器,研究了用双真空（真空感应熔炼＋真空自耗重熔）工艺生产的钴基高温合金ＧＨ１８８中稀土镧化物的析出形貌与类型以及添加的微量元素Ｍｇ晶界偏聚的特性。研究结果表明,采用双真空工艺重熔后,合金中的镧化物呈不均匀分布,导致以它为形核点析出的部分碳化物也分布不均,使其弥散强化效果变差。该合金中的镧化物主要有Ｌａ２Ｏ３,Ｌａ２Ｏ２Ｓ,ＬａＯＳ２,Ｌａ２Ｓ３等类型。另外,微量元素Ｍｇ在合金中的晶界偏聚较为明显,这将降低合金的热加工性。因此,ＧＨ１８８合金中应限制元素Ｍｇ的含量或不加Ｍｇ     

铝合金中镁的快速测定

介绍了铝合金中镁的快速测定方法，提出了运用该方法应注意的问题及其优点。     

Revealing the Subsurface Basal 〈a〉 Dislocation Activity in Magnesium Through Lattice Rotation Analysis

Metallurgical and Materials Transactions A - A method was proposed in this study to reveal the subsurface basal dislocation activity in Mg-Y alloy and determine the corresponding Burgers vector....     

Warm-temperature tensile ductility in Al−Mg alloys

Several binary and ternary Al alloys containing from 2.8 to 5.5 wt pct Mg were tested in tension at elevated temperatures (200°C to 500°C) over a range of strain rates (10⁻⁴ to 2.0 s⁻¹). Tensile ductilities of up to 325 pct were obtained in binary Al−Mg alloys with coarse grains deformed in the solute-drag creep regime. Under test conditions in which solute-drag creep controls deformation, Mg in concentrations from 2.8 to 5.5 wt pct neither affects tensile ductility nor influences strain-rate sensitivity or flow stress significantly. Strength is shown to increase with increasing Mg concentration, however, in the power-law-break down regime. The solute-drag creep process, which leads to superplastic-like elongations, is shown to have no observable grain-size dependence in a binary Al−Mg material. Ternary alloying additions of Mn and Zr are shown to decrease the strain-rate sensitivity during solute-drag creep, negatively influencing ductility. An important cause of reduced ductility in the ternary alloys during creep deformation is found to be a transition from necking-controlled failure in the binary alloys to cavitation-controlled failure in the ternary alloys investigated. An increase in ternary element concentration, which can increase the relative volume percentage of proeutectic products, increases cavitation.     

First-Principles Investigation of the Interfacial Stability,Precipitate Formation,and Mechanical Behavior of Al3Li/Al3Zr/Al Interfaces

Metallurgical and Materials Transactions A - Precipitates including Al3Li, Al3Zr and core–shell structured Al3Li (Al3Zr) produce significant strengthening effects in Al-Li alloys by means of...     

The interface phase in Al−Mg/Al2O3 composites

Auger and electron diffraction studies of Al₂O₃ isolated from a composite prepared by introducing fibers into a vigorously agitated Al−Mg melt indicated the presence of MgAl₂O₄ on the fiber surface. The evidence suggested that the spinel was present as discrete crystals. The thickness and coverage of the spinel is likely to vary with processing conditions. R. MEHRABIAN formerly with the University of Illinois     

New annealing textures in commercial Al−Mg alloys

A number of new textures have been observed in rolled and annealed magnesium-bearing aluminum alloys. The textures contain various proportions of {100} <013> or {100} <015> oriented material, together with components near {110} <332>, or {2, 13, 15} <13, 10, 11> or {4, 11, 14} <11, 6, 8>. They result from recrystallization, and involve the migration of high-angle boundaries similar to those associated with the formation of the more commonly observed cube texture. The origin of these textures is explained in terms of current theories of recrystallization texture formation, and their occurrence is attributed to the absence of {358} <835> and {110} <112> components in the rolling texture. This in turn is attributed to preferred orientations in the as-cast starting material prior to rolling.     

铝脱氧曲轴钢中镁含量的计算分析

采用热力学软件FactSage计算分析了精炼渣成分、Als含量、精炼温度对钢水中镁含量的影响,并通过试验对计算结果进行验证。结果表明:在1 600℃,随着精炼渣碱度的升高以及渣中Al2O3、FeO含量的降低,钢水中Mg含量增加;随着渣中MgO含量的升高,钢水中Mg含量先升高后降低,当渣中w(MgO)为8%时,钢水中w(Mg)达到最大值11.9×10-6;而w(Al2O3)为30%,碱度为15时,钢水中w(Mg)达到最大值11.9×10-6。     

Eu2+在BaM(M=Zn,Li,Mg)Al10O17基质中的发光性能

用燃烧法制备了掺杂不同离子的β-Al2O3结构基质,并探讨了Eu2+在此基质中的发光。Eu2+在Zn-β-Al2O3基质中的发射光谱发生蓝移,在一定程度上解决了绿色拖尾问题。     

高炉炉渣中钛、镁、铝最优配比

以承钢现场渣为基准,研究了钛、镁、铝对炉渣黏度、熔化性温度和脱硫的影响。研究结果表明:在Ca OAl2O3-Si O2-Mg O-Ti O2五元渣系中,钛、镁、铝对炉渣性能的影响较大。随着Mg O质量分数增加,熔化性温度先降低后升高,黏度呈降低趋势,脱硫能力先升高后降低;随着Al2O3质量分数的增加,熔化性温度先降低后升高,黏度变化复杂,脱硫能力降低;随着Ti O2质量分数的增加,熔化性温度和黏度呈升高趋势,而脱硫能力降低。当炉渣碱度为1.12时,炉渣适宜成分:Mg O质量分数约为13.95%,Al2O3质量分数约为13.75%,Ti O2质量分数控制在10.57%以下。合理控制炉渣中钛、镁、铝的配比,对改善炉渣性能和提高高炉生产有重要意义。