LC9铝合金热扭转晶粒细化

ＬＣ９铝合金在７７３Ｋ热扭转中显微组织由粗大的柱状晶转变为细等轴晶。研究表明：其晶粒细化的过程为：位错的聚集；亚晶网络的形成；亚晶界面两侧晶体位向差的增加；亚晶界转变为晶界。从而细晶网络形成。     

SiCp/2024铝基复合材料的超塑性变形行为研究

对经过热处理和冷轧后的体积分数为17％，尺寸为3．5μm的SiC颗粒增强2024铝合金薄板在753－853K范围内进行了超塑性实验研究. 结果在813K时以10^-1/S的变形速率下获得了259％的最大延伸率，最大应力敏感系数为0．25复合材料的变形激活能值在753－793K范围内为144kJ/mol，在813－853K内为202kJ/mol，接近纯铝的晶格扩散激活能值142kJ/mol。复合材料的变形机制主要为基体晶粒滑动机制。     

Superplasticity and superplastic bulging behavior of ZrO<Subscript>2</Subscript>/Ni nanocomposite

ZrO2/Ni nanocomposite was produced by pulse electrodeposition and its superplastic properties were investigated by the tensile and bulging tests. The as-deposited nickel matrix has a narrow grain size distribution with a mean grain size of 45 nm. A maximum elongation of 605% was observed at 723 K and a strain rate of 1.67×10-3s-1 by tensile test. Superplastic bulging tests were subsequently performed using dies with diameters of 1 mm and 5 mm respectively based on the optimal superplastic forming temperature. The effects of forming temperature and gas pressure on bulging process were experimentally investigated. The results indicated that ZrO2/Ni nanocomposite samples can be readily bulged at 723 K with H/d value (defined as dome apex height over the die diameter) larger than 0.5, indicating that the nanocomposite has good bulging ability. SEM and TEM were used to examine the microstructure of the as-deposited and bulged samples. The observations showed that significant grain coarsening occurs during superplastic bulging, and the microstructure is found to depend on the forming temperature.     

W6Mo5Cr4V2—45~＃钢的相变超塑性焊接

本文介绍了相变超塑性焊接技术。试验表明．Ｗ６Ｍｏ５Ｃｒ４Ｖ２－４５＃钢采用循环相变温度区间５２０～８２０℃．应力为σ△＝５０ＭＰａ。σ＝２０ＭＰａ．经８次循环的工艺可实现超塑性焊接。这种焊接工艺具有显著的优越性，是一种值得深入研究的新工艺。     

SiCP/LYl2复合材料超塑变形局部液相现象分析

用扫描电镜等方法对碳化颗粒强化LY12铝合金基复合材料超塑变形时出现的局部液相现象进行了研究分析.结果表明局部液相是导致该复合材料在518℃以上高温拉伸试样过早断裂的主要原因之一,为该材料超塑成形工艺参数的确定提供了参考依据.     

水淬调质态40Cr钢超塑性的研究

研究了 40Cr钢经水冷淬火和高温回火后的超塑性。结果表明 :40Cr钢的晶粒尺寸为 1 0～ 1 5 μm ,在温度为 75 0℃、初始应变速率为 1 0×1 0 - 3s- 1 的拉伸变形条件下 ,超塑伸长率为 30 4 % ,流变应力为 63 0MPa ,应变速率敏感性指数m值为 0 2 2 7,超塑性变形的机制可描述为原子扩散控制的晶界滑动。     

Effects of cooling rate on mechanical properties of near-eutectic tin-lead solder joints

This paper reports the results of a study on the effect of the cooling rate during solidification on the shear creep and low cycle shear fatigue behavior of 60 Sn/40 Pb solder joints, and on bulk solder tensile properties. Solder joints were made with three different initial microstructures by quenching, air-cooling and furnace-cooling. They have similar steady-state strain rates under creep at relatively high shear stresses (i.e. in the matrix creep region) but creep at quite different strain rates at lower shear stresses (i.e. in the grain boundary creep region). These results are ascribed to the refined grain size and less lamellar phase morphology that results on increasing the cooling rate. Tensile tests on bulk solders that were cold-worked, quenched and furnace-cooled show that a faster cooling rate decreases the ultimate strength and increases the ductility at low strain rates. The fatigue life of quenched solder joints is shown to be longer than that of the furnace-cooled joints.     

激光超塑性成型技术研究

本文探讨了激光超塑成型技术中所涉及的合金板材制备、光能耦合及成型工艺，给出了标样拉伸实验和实际工件成型的结果，并对金相组织进行了分析．     

超塑20钢的空洞与断裂行为

本文在获取２０钢超塑性的基础上，对其空洞与断裂行为进行了研究，通过观察空洞的产生和测定空洞的长大，提出了一种超塑材料空洞的形核模型。研究确认，超塑２０钢的断裂由沿晶和穿晶两种断裂类型组成。     

Superplasticity in Aluminium Brass(HAl 66-6-3-2)

1.IntroductionSuperplasticity is not merely a specialphenomenon for certain specific alley,but isone of the intrinsic properties of metallicmaterials[1].When the internal and externalconditions are suitable,superplasticity ofmetal materials will be presented.