NOTCH SENSITIVITY OF ALUMINUM-LITHIUM ALLOYS IN FATIGUE

In order to evaluate the notch fatigue strength and notch sensitivity of aluminum-lithium, 2090 and 8090, alloys, rotary bending fatigue tests have been carried out using circumferentially notched specimens with different stress concentration factors. The results were compared with those of traditional aluminum, 2024T4 and 7075-T6511, alloys. It was found that 2090 and 8090 alloys showed superior notch fatigue strength in comparison to the conventional aluminum alloys. The notch sensitivities to the crack initiation limit of the aluminum-lithium alloys were lower than those of 7075-T6511, while they were nearly equal to those of 2024T4 for blunt notches. The notch sensitivities to the crack propagation limit were also lower in aluminum-lithium alloys, in particular the 8090 alloy, than in the conventional aluminum alloys. It was suggested that the decreased notch sensitivities of the aluminum-lithium alloys were attributed to both the crack propagation mode and the excellent propagation resistance related to their microstructures.     

铝硅系铸造铝合金中的铁相

论述了ZLl08和YL1l3合金中的(FeMn)3Si2Al15球状多面体形态及偏析。铁在铸造铝合金中通常以针状化合物的形态出现在金相组织中，使合金力学性能恶化，加适当比例的锰可以中和铁的有害作用，使之改变成为汉字状、鱼含状、花卉状和球状多面体形态。但(FeMn)3Si2Al15球状多面体，因硬度高，给机械加工带来困难，应使之尽可能均匀分布互数量要少。当铁锰含量偏高时，可采用简单的工艺方法将铁锰含量降至适当的水平，使(FeMn)3Si2Al15相尽可能少。     

IMPINGEMENT CASTING PROCESS OF IMMISCIBLE ALLOYS

Experimental work on impingement casting process of Pb-Zn, Pb-Zn-Sn and Al-Pb systems was carried out. Rapid mixing of immiscible liquid metals was achieved in an arrow-shaped mixing chamber due to vigorous turbulence. The particle size distribution in the castings fitted lognormal curve well. Pb-Zn-Sn system showed the smallest geometric average particle diameter and geometric standard deviation due to low interfacial tension. Various mechanisms of agglomeration were examined and related to the particle sizes. Gravitational sedimentation was shown to be a major parameter governing the agglomeration and hence the final microstructure. The geometric connectivity effect of volume fraction was studied by graphical simulation. When the volume fraction of the dispersed phase was above 30 percent, major portion of the particles were interconnected.     

高强度低密度大模量菲晶态Ai—Li合金

利用单辊快速凝固装置制备出高强度、低密度、大楼量的非晶态Ａｌ６１Ｌｉ２．５Ｙ２５Ｎｉ１１．５（ｗｔ－％）合金，其最大拉伸断裂强度、显微硬度和弹性模量分别为１０３９ＭＰａ、４８８ＤＰＮ和９８．７ＧＰａ．与同成分的晶态合金相比，具有较高的电极电位、较宽的电压钝化区，其腐蚀抗力为晶态合金的７倍．在恒加热速率的晶化过程中出现４个晶化峰，晶化激活能的计算表明，Ａｌ６１Ｌｉ２．５Ｙ２５Ｎｉ１１．５非晶合金的晶化过程为一级反应．     

高强度低密度大模量非晶态Al—Li合金

利用单辊快速凝固装置制备出高强度，低密度，大模量的非晶态Ａｌ６１Ｌｉ２．５Ｙ２５Ｎｉ１１．５（ｗｔ－％）合金，其最大拉伸断裂强度，显微硬度和弹性模量分别为１０３９ＭＰａ，４８８ＤＰＮ和９８．７ＧＰａ，与同成分的晶态合金相比，具有较高的电极电位，较宽的电压钝化区，其腐蚀抗力为晶态合金的７倍。在恒加热速率的晶化过程中出现４个晶化峰，晶化激活能的计算表明，Ａｌ６１Ｌｉ２．５Ｙ２５Ｎｉ１１．５非晶合金的晶     

炸药现场混装技术在大型露天煤矿抛掷爆破中的应用

结合炸药现场混装技术在黑岱沟露天煤矿抛掷爆破中的应用实践,介绍了适于大型露天矿山使用的乳胶基质地面站、铵油炸药地面站生产技术,多功能装药车系统结构及现场混装炸药的性能。通过分析现场爆破效果、经济与社会效益,阐述了该项技术的应用优势,为大型露天矿山爆破施工提供了经验。     

复杂环境烟囱爆破拆除的安全防护

为了安全、高效地拆除砖结构烟囱,根据待拆烟囱与相邻建构筑物距离较近的情况,采用定向爆破拆除方案。将爆破切口位置布置在离地面高0.8m处,采用正梯形切口,通过精心设计和施工实现了烟囱准确定向倒塌。采取开挖减振沟、铺设缓冲垫层等措施减小振动,采用湿草垫、竹板对切口严密覆盖,防止爆破飞石的飞散。爆破未对周边建筑设施产生影响,取得了良好的效果,可为类似工程提供参考。     

聚烯烃催化合金技术的新进展

综述了用高效球形负载化Ｚｉｅｇｌｅｒ－Ｎａｔｔａ催化剂经多段聚合工艺直接合成两种以上聚烯烃多相合金材料的原理,工艺方法及所得材料的结构和性能特点,并对这种技术的最新进展和发展前景作了介绍。     

精铸技术在模具制造中的应用

本文叙述了熔模精铸模具、陶瓷型精铸模具、石膏型精铸模具和加压精铸模具的应用情况，由于精铸模具比机加工模具缩短了生产周期．降低了制造成本．故有很好的发展前景。文章还对陶瓷型精铸模具技术提出了六点改进意见。     

体可视化的快速光线投射算法

对规则标量数据场的体绘制算法进行了讨论。在此基础上给出了一种快速的自前向后的光线投射算法,利用多边形扫描转换减少了投射光线的数量。通过光线的参数化表示方法减少了光线与数据场求交的计算量。并且通过将Bresenham算法扩展至三维,对光线通过三维扫描转换以进行体素化,从而避免了对空间的采样从而加速了光线投射的效率,而且通过利用OpenGL提供的函数接口,简化了算法的实现过程。     

Al-Mg合金的晶界内耗

研究了退火、淬火状态下 Al-Mg 合金的晶界内耗。实验表明,随 Mg 含量的增加,晶界内耗峰的峰宽和弛豫强度单调下降,峰位开始移向高温,后又移向低温;高温淬火处理能压低 Al-2.4wt-%Mg的晶界峰,但对其它低 Mg 含量试样不敏感,一定温度的保温能使压低的晶界峰回升。     

TbDyFe合金的组织和磁致伸缩性能

定向凝固ＴｂＤｙＦｅ合金具有（１１２）择优取向，热处理能明显地改变显微镜组织和磁致伸缩性能，在１１００℃真空处理２ｈ后，磁致伸缩性能最好，空冷和炉冷对磁致伸缩性能影响不大，富稀土相的球化和晶粒吞并长大，减小了磁化过程中９０°磁畴转动的阻力，是高温处理提高磁致伸缩性能的根本原因。     

FATIGUE-MICROSTRUCTURE RELATIONSHIPS IN SOME AGED ALUMINIUM ALLOYS

Abstract Aluminium–copper–magnesium alloys show a high response to age hardening but have relatively poor fatigue properties, whereas the reverse is true for aluminium magnesium alloys. Small additions of silver (∼0.1 atomic %) change both the type and dispersion of precipitates in Al–Cu–Mg alloys and promote age hardening in Al–Mg alloys in which it is normally absent. The paper is concerned with the effects of silver on the behaviour of representative Al–Cu–Mg and Al–Mg alloys tested under fatigue conditions.
Despite the fact that silver increases the response to age hardening in Al–Cu–Mg alloys, the fatigue endurance limit is reduced. This effect is even more marked with the alloy Al–5% Mg in which the 0.2% proof stress was increased from 85 to 200 MPa by adding silver, whereas the fatigue endurance limit fell from ±87 to ±48 MPa. In both systems, silver promotes formation of finely dispersed precipitates, and the poor fatigue properties are associated with the concentration of dislocations in intense slip bands. On the other hand, when large precipitate particles are present, dislocations are more uniformly dispersed and the fatigue properties are improved.     

Co-Ce合金的高温氧化行为

研究了纯Co、Co-2Ce及Co-5Ce合金在600～800℃(的温度下在)空气中的氧化行为.纯Co的氧化基本符合抛物线规律.Co-Ce合金的氧化过程近似由二个抛物线阶段组成.Co-Ce合金表面的氧化膜由Co的氧化物和CeO2组成.含Ce氧化物继承了原始合金中的金属间化合物相Co17Ce2的分布形貌.Co-5Ce合金的氧化比Co-2Ce合金快.合金内氧化严重.还讨论了Co-Ce合金的氧化机制.     

Cu-Zn 合金马氏体相变热力学

假定 Cu-Zn 合金马氏体相变中新、旧原子存在 Bain 机制所示的对应关系,则沿用已知的热力学数据,以 BWG 模型处理 Cu-Zn 合金的有序问题,推导出相变驱动力ΔG~(β′→α′)的普遍表达式。以该式计算了Cu-Zn 合金马氏体相变的平衡温度 T(?)及马氏体相变点 M_s,其中 M_s 与实验结果很好吻合。计算证明,母相有序化是 Cu-Zn 合金发生热弹性马氏体相变的必要条件,有序度对 M_s 有显著的影响。     

Cu—Al 合金马氏体相变热力学

依据规则溶液模型,在充分利用 Cu-Al 系相图的基础上,导得 Cu-Al 合金的一些热力学参量。应用统计模型处理了 Cu-Al 合金中涉及马氏体相变的体心立方及面心立方两种结构的有序相变,直接从理论上计算了不同成分 Cu-Al 合金α和β相的平衡温度 T~*,有序α′与β′相的平衡温度 T_0,以及马氏体相变点 M_s,其中 M_s 与实验值非常吻合。计算还表明 Cu-Al 系中 T_0比 T_0~*更高。     

大气下火焰法合成金刚石薄膜

本文介绍了用氧-乙炔火焰法在大气下合成金刚石薄膜的实验结果,初步研究了基板温度对金刚石晶体生长速度、结晶习性的影响,指出了在金刚石(111)及(100)晶面上外延单晶金刚石膜的温度范围,还探讨了氧对薄膜的质量均匀性的影响。     

Cu-Zn-Al 形状记忆合金马氏体相变热力学

对不同成分的 Cu-Zn-Al 合金中无序α与β相的平衡温度 T_0~*,有序α′与β′相的平衡温度 T_0(母相为 L2_1有序结构)及各种有序母相所得 M_s 进行了系统的计算。用电阻法测试了直接淬火及分级淬火试样的相变温度。结果表明,当母相为 L2_1有序结构时,理论计算的 M_s 值与分级淬火试样 M_s 的实验值吻合。计算还证明,相对无序结构母相 B2或 DO_3有序化均引起 M_s 下降,前者使 M_s 下降更多。     

ENVIRONMENTAL EFFECTS ON CRACK PROPAGATION IN ALUMINIUM ALLOYS

Abstract Crack propagation rates have been measured in two aluminium alloys under cyclic and static loading, in air, and in salt solution. On the basis of these results, a model is proposed, whereby corrosion fatigue crack propagation may be interpreted in terms of fatigue and static stress corrosion characteristics. Two interacting processes are operative; one is "stress assisted dissolution", which tends to inhibit mechanical failure by crack blunting and microbranching. The other is "environment assisted fracture" which occurs too rapidly for dissolution to occur. One or other of these processes is always observed to be dominant. This proposal is discussed in relation to other recent models for corrosion fatigue cracking. The effects of frequency, waveform and mean stress variations are also considered.