高硅铝合金的研究现状及展望

高硅铝合金由于具有很多优点,近些年来被广泛开发和应用。对高硅铝合金的特点及应用进行了简要介绍;评述了熔炼铸造、快速凝固与粉末冶金、喷射成形这几种制备高硅铝合金的工艺和优缺点,以及高硅铝合金的国内外发展动态;对利用热喷涂技术制备高硅铝合金进行了展望。     

快速凝固硅铝合金材料的组织与性能

针对电子信息工业对新型结构功能一体化电子封装材料的应用需求,采用喷射成形与热压致密化相结合的方法制备高Si含量(质量分数为50%~70%Si)的系列Si-Al合金,并利用金相显微镜、扫描电镜、硬度测试仪、热膨胀仪等手段研究该材料的显微组织、力学性能和热物理性能。结果表明,喷射成形高硅铝合金的沉积态显微组织细小弥散,初生硅呈不规则形状,均匀弥散地分布在铝基体中;对沉积坯件进行适当的热压致密化处理可以有效地消减喷射成形制坯工艺过程中所形成的疏松和孔洞,提高材料的致密度。经热压致密化处理的喷射成形高硅铝合金材料具有优越的热物理性能以及良好的力学性能,是一种综合性能优越的结构功能一体化电子封装材料。     

喷射沉积技术的发展及其在合金制造中的应用

喷射沉积技术是一种新的金属成形工艺,作为高性能结构件的一种先进制坯技术,应用愈来愈广泛.本文对该工艺进行了综述,并介绍了喷射沉积技术的特点及其在高温合金和硅铝合金制造中的应用.     

喷射成形Al22Si5Fe3Cu1Mg的高温耐磨机制

采用常规铸造和喷射成形两种工艺制造Al22Si5Fe3Cu1Mg高硅铝合金,研究磨损温度对合金摩擦行为和磨损机理的影响。结果表明:由于喷射成形高硅铝合金具有组织细小、成分均匀等特征,在磨擦过程中表现出更好的抗磨损性能。合金的磨损机制随着温度的升高而发生转变,低于临界温度时为磨粒和黏着磨损混合形式,高于临界温度后转变为剥层磨损。合金在高温下磨擦时,由于氧化速度较快,形成的氧化物改善合金的抗磨损性能,但存在一个临界温度,当超过临界温度时,两种工艺下的合金均由轻微磨粒和黏着磨损混合形式转变为严重的剥层磨损,喷射成形合金在不同高温下的抗磨损性能均显著优于铸造合金的,且其磨损机制转变临界温度比常规铸造合金的高约100℃。     

微细电火花加工高硅铝合金材料蚀除机理研究

对高硅铝合金微细电火花加工材料蚀除机理进行了分析研究.通过Quanta 200F环境扫描电镜对喷射成形Al-50 wt％ Si合金的微观结构进行观察,并建立简化模型.研究了在铜电极和钨电极两种加工过程中材料的蚀除形式,分析了材料的蚀除过程.     

喷射成形7055铝合金的显微组织和力学性能

采用全自动控制往复喷射成形工艺制备了7055铝合金的大规格喷射成形锭坯.通过显微组织分析和力学性能测试,研究工业规格喷射成形7055铝合金的初始组织、挤压工艺及热处理制度对显微组织和力学性能的影响.结果表明,喷射成形7055铝合金锭坯规格可达d 260 mm×1600 mm,晶粒为等轴状,粒度宏观均匀,主要在20～30 μm,组织无明显宏观偏析,锭坯致密度达到98.2 %.喷射成形态材料的T6态σb为500～543 MPa,显示控制往复喷射成形铝合金锭坯冶金质量优越.喷射成形锭坯经过小挤压比变形后达到全致密,大规格产品的T6态纵向σb提高到745 MPa,δ为12.8 %.     

喷射成形7475铝合金的显微组织与力学性能

采用全自动控制往复喷射成形工艺制备了大规格7475铝合金锭坯。研究工业规格喷射成形7475铝合金的初始组织、挤压工艺及热处理制度对显微组织和力学性能的影响。结果表明,喷射成形7475铝合金锭坯规格可达Ф360mm×1200mm,晶粒为等轴状,粒度宏观均匀,主要在30～40μm,组织无明显宏观偏析,锭坯致密度达到97%。喷射成形锭坯经小挤压比变形后达到全致密,T6态(480℃×4h+135℃×16h)合金性能最优,σb为625～635MPa,δ为12%～12.6%,表明控制往复喷射成形铝合金锭坯冶金质量优越。     

高硅铝合金汽车活塞半固态触变成形的试验研究

对采用喷射沉积获得的高硅铝合金半固态坯料进行了汽车活塞触变成形工艺的试验研究,获得了该合金触变成形的工艺参数,其中坯料的触变性、模具的设计结构、二次加热温度,压力控制是触变成形工艺的关键.并对触变成形后的材料进行了热处理优化试验和成形前后材料的微观组织进行了观察以及密度测定.     

高硅铝合金电子封装材料研究进展

阐述电子封装材料的基本要求,论述高硅铝合金材料的研究概况及其性能特点,分析熔炼铸造、浸渗法、快速凝固/粉末冶金和喷射沉积制备方法的优缺点,并指出高硅铝合金电子封装材料的发展方向。     

喷射成形快速凝固技术在铝合金中的应用

喷射成形作为一种新兴的快速凝固技术,已经被广泛地应用于研制和开发各种高性能的快速凝固材料,近年来发展非常迅速。叙述了喷射成形技术在高强铝合金系,高比强、高比模量Ａｌ－Ｌｉ合金系,低膨胀、耐磨Ａｌ－Ｓｉ合金系,耐热、高强Ａｌ－Ｆｅ合金系及铝基复合材料等方面的研究概况及应用;着重讨论了该技术对不同系列铝合金的组织和性能的影响。     

Hardness and microstructural developments of spray formed aluminium alloys with high Mg2Si content during hot extrusion and heat treatment

Abstract

Spray forming offers the possibility of producing alloys with very fine, homogeneous microstructures. Even materials with high contents of intermetallic precipitates, which cannot be produced by casting because of the high solidification rates required, can be distributed homogeneously. Alloying aluminium with high contents of Mg and Si (>20 wt-%Mg₂Si) gives an increase in stiffness plus a significant reduction in density, but a very fine distribution of the Mg₂Si particles in the aluminium matrix is required. Therefore, such alloys are commonly produced by spray forming. Post-spraying processes such as forming and heat treatment are generally carried out to optimise properties. To examine the microstructure and hardness as a result of subsequent processing, aluminium alloys with high Mg₂Si content (22–30 wt-%) have been produced under a variety of spray forming conditions. The duration and temperature of heating before extrusion were varied. In addition, some specimens were preheated without extrusion. The influence of subsequent heat treatment was investigated by varying the age hardening parameters. Hardness measurements were conducted and the distribution and size of the precipitates were evaluated by light microscopy. Image analysis was used to study the coarsening behaviour of primary Mg₂Si. The results indicate that the subsequent processing conditions have a strong influence on the microstructure and hardness of the material. Further, a significant dependence of coarsening rate during subsequent processing on the initial state of the material after spray forming was observed. Knowledge of correlations between process parameters and microstructural development offers the possibility of optimising the hot extrusion and heat treatment parameters for high Mg₂Si containing aluminium alloys.     

铝及铝合金有机聚合物喷涂膜冶国内外标准探析

静电喷涂是应用较广的一种铝合金表面处理方式,国内外对铝及铝合金有机聚合物喷涂膜都有相应的标准规范。从外观、膜厚、光泽等方面,详细分析了国内外铝及铝合金有机聚合物喷涂膜性能要求和检测方法的异同,为我国国家标准的修订提供参考。     

细晶铝锭熔炼的6063铝合金铸态组织与性能研究

细晶铝锭是采用纯铝的电解设备,通过向铝电解槽中添加TiO2,直接电解生产的晶粒细化的铝锭。采用细晶铝锭熔的6063铝合金与AlTi5B1、AlTi5中间合金细化的6063铝合金铸态组织性能进行对比研究。结果表明:AlTi5B1中间合金细化效果最好,AlTi5中间合金细化效果最差,细晶铝锭的细化效果居中;6063铝合金铸态组织硬度,在钛含量低于0.05%时,主要由Mg2Si含量决定,晶粒大小对硬度的影响较小。     

Korrosionsermüdung von Aluminium- und Magnesium-Gußlegierungen

Corrosion fatigue of cast aluminium- and cast magnesium alloys The fatigue properties of the aluminium cast alloys AlSi7Mg and AlSi10Mg, magnesium high pressure die-cast AZ91 hp and AM60 hp, as well as low-pressure permanent mould casting AZ91 hp were determined at numbers of cycles to failure between 10⁵ and 10⁹ in ambient air and in saltwater spray. The investigations were performed at constant amplitudes and in addition at varying load amplitudes for aluminium cast alloy AlSi10Mg and low-pressure permanent mould casting AZ91 hp with a high-frequency testing facility (20 kHz ultrasound). The SN-curves of the aluminium cast alloys and of the magnesium low-pressure permanent mould casting are steeper in corrosive environment than in laboratory air. No endurance limit could be detected up to 10⁹ cycles in both environments. The magnesium high pressure die-cast alloys do not have an endurance limit in saltwater spray, whereas an endurance limit could be detected in laboratory air. The life time curves for in-service loading conditions are about parallel to the SN-curves for ambient air, but steeper for corrosive environment. The reason for the reduced fatigue properties in corrosive environment are accelerated crack initiation and higher crack propagation rates. Material defects may lead to a large scatter of the fatigue data for testing in air as well as in saltwater spray. Corrosion pits are formed on the surface of both light-weight alloys at higher number of cycles. They become crack initiation sites.     

汽车用铝合金的研究进展

介绍了铝合金在现代汽车工业中的应用，从合金元素、热处理工艺和冲压成形技术等方面分析了国内外汽车用铝合金的研究现状与发展趋势，指出铝合金是现代汽车工业最理想的材料之一。针对我国汽车用铝合金的开发与应用所存在的问题，提出了加速我国汽车用铝合金发展的建议和对策。     

Improving the corrosion protection of aluminium alloys using reactive magnetron sputtering

Most high strength aluminium alloys used in the aircraft industries are susceptible to corrosion. Up to now hexavalent chromium is the conventional corrosion inhibitor. Because chromium in hexavalent state is carcinogenic, it is necessary to develop effective alternative inhibitor systems. We investigated magnetron sputtered substoichiometric and stoichiometric aluminium nitride (AlN_x with x ? 1) coatings for corrosion protection of aluminium alloys 2024-T3, 6061-T4 and 7075-T6. The corrosion behaviour of the treated surfaces was tested by anodic polarization scanning and salt spray testing.From the polarization curves it can be concluded that magnetron sputter coating with AlN_x leads to a higher pitting potential of the three aluminium alloys investigated. The salt spray tested samples also confirm the protective effect of the coatings. In addition we found that AlN_x layers with high nitrogen content lead to a stronger shifting in pitting potential than those with low nitrogen content. Anyway, the results of the salt spray testing show that particularly nitrogen-rich AlN_x layers are less stable towards NaCl electrolyte.     

Hydrogen evolution from aluminium in reactor containment spray solutions

Three different aluminium alloys were exposed to conditions similar to BWR and PWR containment spray waters at 50, 100 and 150°C. BWR de-ionized water gives corrosion rates of at most 0.05 mm/year and hydrogen concentrations less than 0.1–1%. By contrast, PWR alkaline solutions give very high corrosion rates and hydrogen contents.     

High temperature oxidation mechanism of dilute copper aluminium alloys

Dilute copper-aluminium alloys were oxidized in air from 700 to 1000 °C. Two distinctive behaviours were observed: alloys with at least 3 wt% aluminium showed excellent oxidation resistance in the whole temperature range. Alloys with 2 wt% or less aluminium exhibited good oxidation resistance up to 800 °C; but as the temperature was further increased, the oxidation rate of these alloys increased and became comparable to that of pure copper. A kinetic model was developed to explain the oxidation behaviour and indirectly determine the amount of dissolved oxygen in the alloys tested. It was found that the oxygen dissolved in alloys with up to 2 wt% Al exceeded its solubility limit in copper, whereas the dissolved oxygen in alloys with higher aluminium contents was below the solubility limit. This difference may account for the significantly different oxidation resistance.