液体轧制Al—Si合金薄带的强韧化

液体轧制是将快速凝固技术引入连续铸轧中形成的一种新的加工方法，研究结果表明，液体轧制Ａｌ－Ｓｉ合金薄带的强度较未变质铸态的提高３９％，塑性指标亦明显提高，这是由于液体轧制过程中液体处于速流动状态和一定压力双重作用下快速结晶凝固成开，从而改变了Ａｌ－Ｓｉ合金薄带的显微组织，尤其是Ｓｉ相的形态，尺寸其分布状态，使薄带获得了明显的强韧化效果。     

快速凝固和直流电处理对铝硅合金中硅形态影响

用氮气雾化法制取了Ａｌ－２１．５４％Ｓｉ合金微粒并进行７００℃重熔处理，对加Ｓｒ变质的Ａｌ－１３．２３％Ｓｉ合金熔体进行了直流电处理。用扫描和透射电研究了不同处理条件对Ａｌ－Ｓｉ合金中共晶硅生长形态的影响。结果表明，快速凝固法制取的合金微粒与重熔处理试样中，共晶硅呈球状和条状。加Ｓｉ变质的共晶硅为弯扭的纤维状，直流电熔体处理后共晶硅转变为圆状，其颗粒尺寸为５０－２００ｎｍ。     

Al-12.6%Si薄带双辊快速凝固成形试验研究

运用双辊快速凝固方法将液态Ａｌ－１２．６％Ｓｉ合金直接制备成厚度为０．１￣０．５ｍｍ的薄带。介绍了这一方法的基本原理、特点和试验设备设计中的关键问题。辊面可控线速度Ｖｒ为２￣８．５ｍ／ｓ,薄带厚度正比于Ｖｒ＾－１／２。薄带组织为细小的初晶α－Ａｌ和极细小的（α－Ａｌ＋Ｓｉ）共晶体,塑性和抗拉强度得到明显改善．     

快速凝固Ni—50Al—5Si—2Fe—0.25Ce合金的催化特性研究

制备了快速凝固Ｎｉ－５０Ａｌ－５Ｓｉ－２Ｆｅ－０．２５Ｃｅ合金,用碱洗抽Ａｌ的方法另以活化,对活化后催化剂的结构特征及其十八腈加氢催化性能进行了研究。结果表明,快凝Ｎｉ－５０Ａｌ－５Ｓｉ－２Ｆｅ－０．２５Ｃｅ前置体合金中含有较多的Ｎｉ２Ａｌ３及ＮｉＡｌ３相;活化后所得到的新型催化剂与常规ＲａｎｅｙＮｉ相比,其孔径尺寸减小,ｆ．ｃ．ｃ．Ｎｉ晶粒细化,点阵参数扩大,在制备伯胺和仲胺两种选择性反应中均显     

低密阻尼金属/金属复合体材料的组织与性能研究

采用快速凝固／粉末冶金法成功地研制出Ａｌ－７．０９％Ｆｅ－１．３４％Ｍｏ－１．４５％Ｓｉ（ＦＭＳ０７１４）合金及其金属／金属复合体材料ＦＭＳ０７１４／１５％Ａｌ和ＦＭＳ０７１４／１０％（Ｚｎ－３０％Ａｌ）,考察了其组织、拉伸性能、阻尼性能和密度,产散锻铝ＬＤ７ＣＳ合金进行了对比。结果表明：ＦＭＳ０７１４合金本身就具有较好的拉伸与阻尼性能。添加纯Ａｌ和Ｚｎ－３０％Ａｌ合金粉均使其强度下降,而 ＦＭＷ     

Ti—Al—Si三元系中β－Ti（Al，Si）和Ti_5（Si，Al）_3的共晶线

通过试验确定了Ｔｉ－Ａｌ－Ｓｉ三元相图中富Ｔｉ角区域的β－Ｔｉ（Ａｌ，Ｓｉ）与Ｔｉ５（Ｓｉ，Ａｌ）３共晶线．用光学金相、Ｘ射线衍射、电子显微镜等方法研究共品组织以及共晶组织中基体和第二相Ｔｉ５（Ｓｉ，Ａｌ）３。所有这些工作是为了在双相合金的合金设计中能合理地选择合金成分．     

凝固条件和镁对Al-Si11.0合金组织的影响

研究了宇向凝固时冷却条件和镁元素对Ａｌ－Ｓｉ１１．０合金树枝晶结构和共晶组织的影响。试验结果表明,随着冷却速度的增加,Ａｌ－Ａｉ１１．０合一次枝晶和二镒分枝间距都显著减小,在较小的冷却速度时,加入镁元素后合金的二镒分枝间距明显增大,而在冷却速度大于１６０Ｋ／ｍｉｎ时,则没有影响。试验还发现,加入镁元素后,冷却速度对共晶成分的影响显示减小,是合 共晶组织变细。在试验范围内,Ａｌ－Ｓｉ１１．０合金中加     

NiAl金属间化合物的快速凝固组织

用单辊快速凝固法制备了Ｎｉ原子分数为０．５３－０．６０的Ｎｉ－Ａｌ金属间化合物薄带，研究了成分与微观组织的关系，发现试样均为Ｂ２型单相ＮｉＡｌ，Ｎｉ０．５３Ａｌ０．４７的快速凝固组织为１０μｍ左右的等轴晶，Ｎｉ０．５６Ａｌ０．４４－Ｎｉ０．６Ａｌ０．４的组织分别为５μｍ左右的不规则和规则柱状晶，发现近理想配比的ＮｉＡｌ在快速凝固时形成针状晶亚结构。     

Si相尺寸对快凝Al－20Si－1．3Cu－1Mg合金机械性能的影响

研究了快速凝固Ａｌ－２０Ｓｉ－１．３Ｃｕ－１Ｍｇ合金在４００℃热暴露不同时间Ｓｉ相在尺寸上的变化及其对挤压态合金室温、高温性能的影响．试验结果表明，Ｓｉ相尺寸对合金的室温性能有一定影响，经４０℃×１０２４小时暴露后，室温拉伸强度从挤压态的３３５ＭＰａ降到２２０ＭＰａ．热暴露后材料的高温（３００℃）拉伸强度开始急骤下降，但随后σｂ下降速度变缓，说明Ｓｉ相尺寸对材料高温拉伸性能的影响不是高温拉伸强度下降的主要因素．较大的Ｓｉ相颗粒是导致材料室温断裂的主要原因．     

8090Al—Li合金的凝固机制

研究了８０９０Ａｌ－Ｌｉ合金在缓慢冷却时的凝固过程，结果表明：Ｌ→αＡｌ＋Ｌ＇反应是基本凝固过程，贯彻始终。由于溶质元素Ｃｕ的严重偏析，使得合金终凝固温度显著降，凝固温度区间扩大，终凝温度在５２５℃左右，但熔体的９０％以上在６３５－５９０℃之间凝固，在最后凝固区溶质大量富集，从而形成了Ｔ２相等低熔点共晶化合物。杂质元素Ｆｅ，Ｓｉ具有强烈偏析倾向。在缓冷过程中，形成形大的Ａｌ３Ｆｅ，ＡｉＬｉｓｉ，…     

Martensitic Transformation and Magnetic-Field-Induced Strain in Magnetic Shape Memory Alloy NiMnGa Melt-Spun Ribbon

A magnetic shape memory alloy with nonstoichiometric Ni50Mn27Ga23 was prepared by using melt-spinning technology. The martensitic transformation and the magnetic-field-induced strain (MFIS) of the polycrystalline melt-spun ribbon were investigated. The experimental results showed that the melt-spun ribbons underwent thermal-elastic martensitic transformation and reverse transformation in cooling and heating process and exhibited typical thermo-elastic shape memory effect. However the start temperature for martensitic transformation decreased from 286 K for as-cast alloy to 254 K for as-quenched ribbon and Curie temperature remains approximately constant. A particular internal stress induced by melt-spinning resulted in the formation of a texture structure in the ribbons, which made the ribbons obtain larger martensitic transformation strain and MFIS. The internal stress was released substantially after annealing, which resulted in a decrease of MFIS of the ribbons.     

Effect of rapid solidification on giant magnetostriction in ferromagnetic shape memory iron-based alloys

Ferromagnetic shape memory Fe–29.6 at.% Pd alloy ribbons prepared by the rapid solidification, melt-spinning method, showed a giant magnetostriction of 830 microstrain when an external magnetic field of 7 kOe was applied nearly normal to the ribbon surface at room temperature. This ribbon’s magnetostriction was several times as large as conventional polycrystalline bulk’s one before rapid solidification. The magnetostriction in the rolling direction depended strongly on a direction of applied magnetic field. We considered that this phenomenon is caused by a rearrangement of activated martensite twin variants just below the austenite phase transformation temperature. We investigated their basic material properties, i.e. the dependencies of magnetostriction on temperature as well as on magnetic angular orientation to the surface, magnetic properties, crystal structure, surface texture morphology and shape memory effect of Fe–29.6 at.% Pd ribbon samples by comparing with conventional bulk sample. It can be concluded that the remarkable anisotropy of giant magnetostriction of ribbon sample is caused by the unique uniaxial-oriented fine grain structure formed by the melt-spinning method. In addition, we confirmed the possibility of rapidly solidified Fe–Pt ribbon as a new kind of iron-based ferromagnetic shape memory alloys for magnetostrictive material.     

Effect of rapid solidification on giant magnetostriction in ferromagnetic shape memory iron-based alloys

Ferromagnetic shape memory Fe–29.6 at.% Pd alloy ribbons prepared by the rapid solidification, melt-spinning method, showed a giant magnetostriction of 830 microstrain when an external magnetic field of 7 kOe was applied nearly normal to the ribbon surface at room temperature. This ribbon's magnetostriction was several times as large as conventional polycrystalline bulk's one before rapid solidification. The magnetostriction in the rolling direction depended strongly on a direction of applied magnetic field. We considered that this phenomenon is caused by a rearrangement of activated martensite twin variants just below the austenite phase transformation temperature. We investigated their basic material properties, i.e. the dependencies of magnetostriction on temperature as well as on magnetic angular orientation to the surface, magnetic properties, crystal structure, surface texture morphology and shape memory effect of Fe–29.6 at.% Pd ribbon samples by comparing with conventional bulk sample. It can be concluded that the remarkable anisotropy of giant magnetostriction of ribbon sample is caused by the unique uniaxial-oriented fine grain structure formed by the melt-spinning method. In addition, we confirmed the possibility of rapidly solidified Fe–Pt ribbon as a new kind of iron-based ferromagnetic shape memory alloys for magnetostrictive material.     

Effects of partial crystallinity and quenched-in defects on corrosion of a rapidly solidified Ti-Cu alloy

Rapid solidification by planar flow casting has been found to have introduced deficiencies, viz. partial crystallinity, air pockets and compositional difference in the ribbons of rapidly solidified Tiin42.9Cuin57.1 alloy. In order to investigate the effects of these deficiencies on the corrosion of rapidly solidified Tiin42.9Cuin57.1 alloy ribbons, electrochemical behaviour of alloy ribbons has been investigated in the acidic chloride environments at room temperature by taking into consideration each side of the alloy ribbon separately. The alloy displayed passivity followed by pitting corrosion. In the as- solidified condition, air pockets appear to be the most detrimental defect from the viewpoint of corrosion resistance of the alloy ribbons.     

Co_(41)Ni_(33)Al_(26)合金冷轧带材相变与阻尼能力

通过热轧和冷轧工艺制备了0.2mm厚的Co41Ni33Al26合金带材,采用1350℃×5h水冷对该带材进行了淬火热处理,用金相显微镜观察了其组织。用微分差热分析仪(DSC)测定了其马氏体转变温度,并用动态热机械谱仪(DMS)研究了其相变及阻尼能力。结果表明,0.2mm的Co41Ni33Al26合金带材的基体为竹节状的粗大再结晶晶粒,其马氏体相变温度比1.5mm厚的板材高约45℃;降温过程中合金带材在140~25℃温度范围出现阻尼峰,其阻尼峰宽明显大于马氏体相变温度范围,后者为121~78℃,表明有新的应力诱发马氏体相变出现;Co40Ni33Al27合金带材的阻尼能力超过0.04,并且温度范围宽,有望成为新型阻尼材料。     

A microstructural study of a melt-spun ultra high-strength alloy steel

Melt spinning in a controlled atmosphere has been used to produce ribbons of an ultra high-strength alloy steel. The microstructure of these ribbons has been investigated using both optical and transmission electron microscopy. Comparison of the microstructure with that produced by conventional solid-state quenching shows that the martensitic structure is refined in the melt-spun ribbon and the formation of alloy carbides suppressed. These factors lead to a considerable increase in hardness of the meltspun ribbon with respect to that of the solid-state quenched material. The occurrence of interlath austenite is discussed in terms of the crystallography of the martensite transformation.     

Fatigue behaviour of ribbon-reinforced composites

The fatigue behaviour of aluminium-based composites reinforced with high-strength steel ribbons has been examined. In the directions both parallel (longitudinal composites) and perpendicular (transverse composites) to the principal ribbon axis the development of the fatigue deformation is controlled by the matrix. The steel-matrix bond does not deteriorate during the initial stages of fatigue. The fatigue limit at 10⁷ cycles was arbitrarily defined in the case of the longitudinal composites as corresponding to approximately the half-destruction of the composite. In this way the limit for a composite with a volume fraction,V _r of 0.25 was around 25% of the fracture strength while with aV _r of 0.34, the limit was raised to about 33% of the fracture strength. The use of an alloy matrix increases the fatigue strength of the composite. The fatigue mechanism in both longitudinal and transverse composites initially involves matrix cracking; this leads to steel-aluminium or aluminium-aluminium debonding parallel to the principal stress axis in specimens fabricated from pre-coated steel ribbons, followed by ribbon fracture. In specimens fabricated by simply rolling together the steel ribbons and aluminium foils, little debonding is evident. The debonding results in a high fracture resistance.     

厚条带Mg-Al-Zn基合金的显微组织研究

利用单辊低速旋铸方法制备出Mg-3%Al-i.2%Zn-0.2%Mn合金厚条带,估算了不同转速下条带的冷却速度,并重点研究了条带正面及其横截面的显微组织.结果表明:单辊低速旋铸条带(300转/分和500转/分)的冷却速度在104K/s和105K/s之间,厚条带的晶粒较铸态组织品粒细小.500转/分的镁合金条带的断面组织晶粒沿横截面分布比较均匀,并基本均为等轴晶区.300转/分条带的自由面出现部分柱状晶,而贴辊面及贴辊面和自由面之间的过度区都为等轴晶.     

Ti-Ni-Cu形状记忆合金快速凝固条带的研究进展

回顾了Ti-Ni-Cu形状记忆合金快速凝固条带的研究进展.主要介绍了Ti-Ni-Cu合金条带的组织结构、晶化行为、织构和析出物、马氏体相变温度及其形状记忆特性.合金条带的铸态组织随工艺参数不同可在非晶-晶态之间变化;独特的析出物和织构影响其相变行为和形状记忆性能;条带具有良好的形状记忆效应和超弹性性能,与体材相比,其相变应变大而相变应力滞后小.总结了研究中存在的问题并展望了未来的研究方向.