Processing,deformation, and failure in superplastic aluminum alloys: Applications of orientation-imaging microscopy

The importance of grain size refinement in enabling superplasticity is reviewed, and the current understanding of grain boundary characteristics is summarized. The application of orientation-imaging microscopy (OIM) methods to the processing response and the deformation and failure modes in superplastic aluminum alloys are illustrated through microtexture analysis and determination of grain boundary characteristics in selected commercial materials. Continuous and discontinuous recrystallization reactions exhibit distinct microtextures and grain boundary characteristics. The application of OIM and microtexture analysis to the evaluation of both deformation and failure mechanisms during superplastic forming is illustrated. This paper was presented at the International Symposium on Superplasticity and Superplastic Forming, sponsored by the Manufacturing Critical Sector at the ASM International AeroMat 2004 Conference and Exposition, June 8–9, 2004, in Seattle, WA. The symposium was organized by Daniel G. Sanders, The Boeing Company.     

铝镁防锈铝合金塑变组织显示方法研究

采用电解抛光和阳极复膜的方法显示铝镁防锈铝合金塑变前后的晶粒（界）组织，实践表明该方法简单，方便，在正交偏振光下观察，效果良好，晶粒（界）显示清晰。     

关于对金属冶炼建设项目安全设施设计编写的思考

根据金属冶炼建设项目安全设施设计编写提纲,围绕安全设施设计编写中常遇到的几个问题进行分析和思考,主要阐述编写安全设施设计的前期准备工作和编写重点。     

稀土Ce对Al-Cu4.5%合金热疲劳性能的影响

在接近材料实际工况的实验条件下,以铝铜合金(Cu4.5%)为研究对象,用自约束型热疲劳实验机对铈加入量不同的合金,进行了热疲劳实验以及热疲劳裂纹萌生及扩展规律的研究。结果表明:在裂纹萌生阶段,不加铈的铝铜合金的裂纹萌生速度明显大于加铈的合金;在裂纹扩展阶段,不加铈的铝铜合金裂纹扩展速度仍是最快。加入0.5?的合金在裂纹形成后期扩展速度明显加快,这是因为合金中出现针状富稀土相,这种针状相割裂了基体,使得合金力学性能降低、热疲劳抗力下降。加入0.3?的合金不论在裂纹萌生阶段还是裂纹扩展阶段,其热疲劳抗力都优于其它成分的合金。     

稀土、锶复合添加对AM60镁合金组织和性能的影响

稀土、锶复合添加对AM60镁合金组织、力学性能和抗热裂性能的影响的研究结果表明,往AM60镁合金中添加稀土后,稀土与合金中的异质形核核心Al9Mn11相或Al(8Fe,Mn)5相反应生成Al-RE-Mn三元相,减少了合金熔体中异质形核核心的数目,从而引起了合金晶粒粗化。往AM60镁合金中复合添加稀土和锶后,锶能够消除稀土引起的晶粒粗化作用,减少晶粒粗化对合金力学性能和抗热裂性能的不利影响,从而提高合金的高温屈服强度,并消除稀土对合金抗热裂性能的恶化作用。     

纳米结构Al2O3+13%TiO2热喷涂喂料的研究

纳米结构的Al2O3 13％TiO2混合粉经过球磨制浆和喷雾干燥，制得了25～50μm的球形大颗粒结构，分别采用高温电炉和高速火焰两种方式，对喷雾造粒的纳米结构Al2O3 13％TiO2颗粒进行了致密化处理，制备了适合热喷涂的纳米颗粒喂料。测试了喂料形貌、晶粒尺寸及物相成分。分析结果表明，应用高温电炉烧结造粒喂料时，在选定的温度范围内(110-1300℃)，喂料的相成分没有改变，晶粒没有显著长大；采用高速火焰烧结造粒喂料，喂料经高温快速激冷，Al2O3晶粒尺寸仍在100nm以下，但因火焰温度高(2500-3200℃)，相成分分析表明，喂料中发生α-Al2O3→γ-Al2O3及金红石TiO2→板钛矿TiO2的转变。     

Si对过共析锰钢力学性能及晶界组织的影响

本文用ＳＥＭ、ＴＥＭ研究了Ｓｉ对过共析锰钢经９５０℃奥氏体化和５６０℃等温处理后的组织及力学性能的影响。结果表明，Ｓｉ提高冲击韧性和延伸率，抑制先共析渗碳体在奥氏体晶界呈连续网状析出，并促进在过共析钢中晶界铁素体的形成，本文重点讨论了含Ｓｉ过共析钢中晶界铁素体的形成机理及其对韧性的影响。     

The Microstructure and Mechanical Properties of the Low Carbon Microalloy Steel by High Voltage Electropulse Heating

The low carbon microalloy steel samples were heated to different temperatures by high voltage electropulse discharge heating method. The temperature of sample increases with the discharge current density. Microstructures were observed by using scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Results show that coexist microstructure of ultrafine ferrite grain and martensite can be obtained by proper high voltage electropulse discharge heating process parameter. The tensile testing indicate that better mechanical properties were obtained, including 758MPa yield strength, 796MPa ultimate strength and 12% total elongation.     

高阻相对La2／3Ca1／3MnO3低场磁电阻效应的影响

实验研究了La2／3Ca1/3MnO3系统晶界上掺杂(YSZ)对其输运性能和磁电阻效应(MR)的影响。样品是由溶胶．凝胶法制成的。通过对样品的电输运特性的测量表明,在掺杂量(x)低于2％时,掺杂引起电阻的增大并降低了金属．绝缘体转变温度;当掺杂量高于2％时电阻逐渐减小,且转变温度增加。而低场磁电阻效应随掺杂量增加,在x=1％时达到最大。     

纳米Fe-10Cr涂层电化学腐蚀行为影响研究Ⅰ.钝化性能

利用磁控溅射技术制备出了晶粒尺寸为20nm-30nm的Fe—10Cr合金涂层．通过动电位极化曲线、电化学阻抗谱图（EIS）和Mott—Schottky分析等电化学测试手段，探讨了Fe—10Cr纳米涂层在0．05mol／LH2SO4＋0．25mol／LNa2SO4溶液中的钝化性能。发现纳米化使材料的活性溶解增强；在钝化膜形成过程中Cr更容易富集，从而更容易钝化；纳米化后，材料表面钝化膜中的载流子密度下降，化学稳定性提高。