Cr、Ni元素对Fe3 Al/钢扩散焊界面组织结构的影响

采用扫描电镜和透射电镜分析比较了相同工艺条件下获得的Fe3 Al/Q235及Fe3 Al/Cr18-Ni8扩散焊界面的组织结构,研究了Cr、Ni元素对Fe3 Al/钢扩散焊界面组织结构的影响.研究表明:Cr、Ni的扩散有利于促进Fe3 Al与钢中Fe、A1元素的扩散结合,使Fe3 Al/Cr18-Ni8扩散焊界面过渡区的宽度较Fe3 Al/Q235界面过渡区大;并且Fe3 Al/Cr18-Ni8扩散焊界面过渡区新形成的Fe3 Al上弥散分布有含Cr、Ni的第二相,使Fe3A1出现了具有不同间距的位错对,甚至位错缠结现象,有利于提高Fe3 Al/钢扩散焊界面的结合强度.     

基体合金元素对SiC/Al界面结合影响的第一性原理及实验研究

采用基于密度泛函理论的第一性原理及实验相结合的方法, 探讨了Al基体中分别掺杂Mg、Si、Cu合金元素对SiC/Al界面结合的影响, 重点考察了合金元素在界面偏聚时的电子结构和成键情况。研究表明: 在未掺杂Al/SiC体系界面结构优化时, 以Si原子为终止面的Brigde结构是最稳定的结合方式; 当合金元素分别替换界面处的Al原子后, 界面处原子的分波态密度、Muliken电荷及成键原子集居数等电子结构参数均有不同程度的变化, 这不仅增加了界面处 Si与Al原子结合, 同时也增强了界面处和亚界面处的Al基体和SiC增强相原子之间的相互作用, 使体系更加稳定, 界面黏着功均有不同提升; 其中掺Mg提升效果最明显, 其次为掺Cu和掺Si; 利用第一性原理计算的掺杂Al/SiC体系黏着功和实验值较为接近且变化规律相同。     

Al/Fe液-固界面扩散反应层生长动力学分析

采用镶嵌式技术制备了Al/Fe扩散偶,在铝熔点以上铁熔点以下进行扩散热处理,对Al/Fe液-固界面扩散反应层的生长动力学进行了分析,并建立了生长动力学方程。结果表明,Fe2Al5是热处理保温过程中唯一生成的新生相。在Fe2Al5连续单相层形成之前,其生长受Al原子和Fe原子的化学反应控制;一旦连续的Fe2Al5单相层形成,其生长则主要依赖于Al原子沿其晶界的扩散控制,且伴随着其晶粒尺寸的长大。在800℃以下热处理,可忽略晶粒长大对原子扩散的影响,其生长动力学方程为:y=2020.96exp(-78490/RT)t0.25。但当热处理温度超过铁熔点的0.7倍后,则不能忽略晶粒长大的影响,应适当减小生长动力学方程中的生长指数值。     

Al含量对Fe－Al无序固溶体性能的影响

本文应用余氏理论，对不同Ａｌ含量的富Ｆｅ区Ｆｅ－Ａｌ无序固溶体进行价电子结构计算和分析，从理论上探讨了Ａｌ含量对合金晶格常数、原子磁矩、塑性以及晶体内原子状态的影响。研究发现，Ｆｅ－Ａｌ无序固溶体的晶格常数、原子磁矩和塑性随含Ａｌ量的变化，是由于合金中Ｆｅ、Ａｌ原子之间相互作用导致原子状态发生变化的结果。     

合金元素对C/Cu复合材料界面结合特性及性能影响的研究

作者采用连续电沉积法,在碳纤维表面沉积单层或复层金属,如Cu、Ni、Cr、Sn等,并通过真空热压扩散制备复合材料.本文研究了合金元素对C/Cu复合材料界面结合特性和组织性能的影响,并定量地研究了复合材料的界面结合强度.     

杂质含量对Al－Fe合金加工软化规律的影响

研究了杂质含量对Ａｌ－２．０％Ｆｅ合金加工软化规律的影响。结果表明，杂质含量较低（０．００４％）的Ａｌ－Ｆｅ合金，在６０％以上轧制率时出现加工软化现象；杂质含量增加（０．０４％）时，在轧制率高达９０％以上方出现加工软化；而杂质含量较高（０．４％）的Ａｌ－Ｆｅ合金在轧制过程中没有出现加工软化。加工软化机制为多边化回复，基体中的杂质元素阻碍回复进行，加入Ｆｅ形成第二相有利于基体净化，从而提高基体的层错能，易于多边化回复进行。     

SiCp/Al系统界面状况对复合材料机械性能的影响

SiCp/Al复合材料的断裂韧性及抗弯强度等机械性能与SiCp/Al系统的界面状况密切相关，研究了二者之间的关系，指出：复合材料的机械性能受界面反应及界面处Si元素的富集两种作用综合的影响，界面反应的影响较大，是决定复合材料机械性能的主导因素，而Si元素富集则居次要地位，不起主导作用。     

间隙元素对中间成分Ti－Al合金某些相变的影响

根据余氏理论的平均晶胞模型，分析了间隙元素对Ｔｉ－Ａｌ系中间相价电子结构的影响，讨论了间隙元素对中间成分Ｔｉ－Ａｌ合金某些相变的影响。     

合金元素对镍铝青铜性能的影响

介绍了海水泵用材料镍铝青铜的主要性能 ,重点讨论了合金元素对镍铝青铜材料的腐蚀性能、金相组织和铸造工艺性能的影响 ,提出了改进铸造镍铝青铜耐腐蚀性能及铸造工艺性能的几点建议     

Site Occupancy of Alloying Elements and Their Effects on the D03 Phase Stability in Fe3Al

The effects of ternary solutes Ti, Co, V, Cr, Ta, W and Mo on the D03 phase stability of Fe3Al intermetallics are investigated by tight-binding linear Muffin-tin orbital method. The predicted site preferences of these elements in Fe3Al are in agreement with the experimental observations. The calculated local magnetic moment of Fe3Al is identical to the experimental. In addition, it is found that the D03 phase stability of Fe3Al doped with Ti, V, Co and Cr depends on ‘energy gap’ of energy band near Fermi level, while the D03 phase stability of Fe3Al doped with Ta, W and Mo may be affected by Madelung energy.     

碳/铝复合材料界面反应对抗拉强度的影响

本文对Ti-B法制备的碳—铝合复材料经各种处理后产生的不同程度的界面反应与其纵向抗拉强度的关系进行了研究。碳—铝界面反应主要从三方面影响复合材料的抗拉强度:①界面结合强度;②界面脆性层;⑨纤维损伤。这三者的作用程度与界面反应程度有关。界面反应不严重时,主要是界面结合强度起作用;反应较严重时,界面脆性层的影响增大;反应很严重时,纤维发生严重损伤,对材料的抗拉强度产生很大的影响。      

铜铝层状复合材料界面特性及深加工研究进展

铜铝层状复合材料因其良好的综合性能而应用于众多领域,其深加工变形性能关系到复合材料的推广与发展。本文介绍了铜铝层状复合材料深加工性能研究现状,总结了深加工过程中复合材料宏观质量缺陷的成因与解决对策;综述了铜铝层状复合材料的界面特征、形成机理、界面层对铜铝复合板材变形性能的影响;从宏观和微观角度汇总了复合材料界面断裂失效机理;概括了复合材料深加工变形过程中界面结构演变规律;基于复合材料协同变形,提出了复合材料界面结构调控机制。文章还对铜铝层状复合材料深加工发展方向进行了展望。     

合金元素对铸造Al-Si-Cu-Mg合金机械性能的影响

应用一元回归正交试验的方法研究分析了Si、Cu、Mg对Al-Si-Cu-Mg铸造合金机械性能的影响,在试验区域内建立了这三种元素含量与机械性能的关系式。考察了不同细化条件对合金性能的作用效果。同时还试验研究了两种微量元素Gd、La对合金机械性能的影响,分析了其作用机理。     

Ductilization of Ni_3Al by Alloying with Substitutional Elements

This paper reviews recent research on ductility improvement of B-undoped Ni_3Al alloys.Ni_3Al binaryalloys with hypostoichiometric compositions show appreciable ductility at room temperature whenthe samples are prepared by recrystallization annealing after cold pressing,although the alloys withstoichiometric and hyperstoichiometric compositions remain brittle.Melt-spun ribbons withhypostoichiometric compositions contain fine anti-phase domains (APDs),while no APD can beseen in melt-spun ribbons with a hyperstoichiometric composition.The ductility inhypostoichiometric Ni_3Al alloys is associated with low ordering energy of the alloys.The addition ofternary elements,which have been classified as γ formers such as Pd,Pt,Cu,Co and Ag.improvesductility of Ni_3Al alloys.Correspondingly,the microstructure of the melt-spun ribbons consists offine APDs.The addition of γ' formers such as Si,Ti,Zr,V,Nb and Ta leads to brittle intergranular frac-ture.No APD was observed in the melt-spun ribbons of these ternary alloys.     

Effect of Iron Morphology and Interfacial Bonding on the Toughening of Al2O3/Fe Composites

Two morphologically different composites comprising an alumina matrix and 20 vol. pct Fe particles have been fabricated by hot pressing technique. Two kinds of microstructures, i.e. a dispersive distribution of Fe particles and a network distribution of Fe particles in alumina matrix, have been produced. Both composites are tougher than the virgin alumina matrix. The fracture toughness of the composite with a network microstructure is much higher than the composite with a microstructure of dispersed particles. For the particulate dispersion microstructure, the main limitation to the toughening is the lack of plastic deformation of the ductile Fe due to the pull out of Fe particles, indicating weak bonding at the Al2O3/Fe interface. For the network microstructure composite, the gauge length of the ductile phase is much larger, allowing the ductile Fe to be stretched to failure between the crack faces. The weak bonding at Al2O3/Fe interface can promote partial debonding and contribute further to toughening in the network microstructure composite.     

Influences of Alloying Elements W, Mo, Cr and Nb on Retained Beta Phase in 47Al Based near γ-TiAl Alloys

The influences of alloying elements W, Mo, Cr, and Nb on retained β phase in 47Al based near γ-TiAI alloys have been studied.The results reveal that the amount of retained β phase is increased by the addition of Cr, Mo, W in rising rank, although the distribution of β phase in Cr-bearing alloys is different from that of Mo- or W-bearing alloys. For Nb-doped alloys, no retained β was found even when 5 at. pct Nb was added. The as-cast microstructural features and the distribution of the β phase in the different alloy families were compared and interpreted in terms of the different segregation behaviour of these elements in Ti.     

Interfacial microstructure of anodic-bonded Al/glass

The interfacial microstructure of anodic-bonded Al/glass was investigated to obtain a better understanding of the bonding process. The experimental results demonstrate that a sodium-depleted region existed in the glass adjacent to the aluminum. Aluminum diffused into the glass for about 500 nm when the Al/glass was anodic-bonded at 250 °C, 700 V and 420 s. Furthermore, a crystalline region about 10 nm thick developed in this aluminum-diffused region of the glass. The crystalline region was greatly aluminum-diffused. No aluminum oxide region existed at the interface. It is therefore concluded that the diffusion of aluminum into the glass is responsible for bond formation. This conclusion does not agree with the conventional anode oxidation model based on the assumption that aluminum does not diffuse into the glass.