钕对4004铝合金变质效果的影响

研究了在熔体温度为720℃保温时间为60min时稀土钕加入量(0%、0.15%、0.3%、0.45%和0.60%)对4004铝合金变质效果的影响.结果表明:当钕加入量低于0.30%时,合金组织和力学性能都没有达到完全变质的状态:当钕加人量为0.30%时,4004铝合金变质效果最好,合金组织中的初晶铝转变为细小的圆状或短棒状,共晶硅也由片状或针状转变为纤维状,合金的抗拉强度达到最大值(197MPa),伸长率也达到最大值(4%);当加入量超过0.30%时,随着加入量的增加,合金的组织开始变得粗大,抗拉强度和伸长率随之降低.     

Effects of novel self-inoculation method on microstructure of AM60 alloy

A novel cast processing method,self-inoculation method (SIM),was proposed.The process involves the addition of self-inoculant to melt,then pouring the melt to a mould through a multi-stream mixing cooling channel.In this paper,the process parameters were investigated.Results indicate that the melt treatment temperature,the amount of self-inoculant added,and the slope angle of the cooling channel are the key factors for SIM process.The optimized parameters are that the melt treatment temperature is between 680 and 700°C;the addition of self-inoculant is between 5wt.% and 7wt.%;and the slope angle of the cooling channel is between 30° and 45°.Further analysis reveals that SIM changes the solidification microstructure of slurry by controlling the nucleation and growth of the primary phase in the melt.     

Thermo-mechanical Analysis of Friction Stir Welding:A Review on Recent Advances

In recent studies, critical research interest exists in the thermo-mechanical analysis of the friction stir welding(FSW) process by numerical simulation. In this review, the thermo-mechanical analysis for FSW is overviewed regarding the computational approaches, the heat generation, the temperature, and the material fl ow behavior. Current concerns, challenges, and opportunities in current studies are discussed considering the application of the thermo-mechanical analysis. Generally, larger computational scale and better computational effi ciency are required to allow better spatial resolution in future analysis. The concepts and approaches demonstrated in the thermo-mechanical analysis for FSW open up quantitative prospects for the design of the FSW process.     

7050铝合金多尺度表面结构抗粘附性能的研究

通过多道喷丸在7050铝合表面构建多尺度复合结构,利用SEM及共聚焦激光显微镜分析合金的表面形貌,利用接触角试验以及平板硫化实验测试合金的表面润湿性以及抗粘附性。结果表明:采用多道喷丸方式在铝合金试样表面获得具有微米级以及纳米级的多尺度复合结构,铝合金表面润湿角接近120°,具有疏水性,硫化实验表明金属表面的抗粘附性能大大提高。     

高锁螺栓连接力学参数关系的实验研究

为了研究高锁螺栓连接过程中拧断力矩、锁紧力矩及预紧力之间的关系,借助普通螺栓连接经典理论推导出了高锁螺栓连接的数学模型。以A286材质的M5、M6、M8型三点高锁螺母及未经自锁工艺处理的高锁螺母与高锁螺栓为实验对象,利用扭拉实验设备,获得了拧断力矩、锁紧力矩及预紧力值。通过推导的数学模型计算出了扭矩系数。实验结果表明:三点高锁螺母及未经自锁工艺处理的高锁螺母的拧断力矩值和扭矩系数值几乎相同。对于三点高锁螺母,收口部位对高锁螺母的拧断力矩几乎没有影响,锁紧力矩是线性叠加到拧断力矩上的。实验结果验证了数学模型的正确性。     

电磁连铸和微合金化对5356铝合金组织性能的影响

研究了不同电源功率、拉坯速率和冷却水量等参数以及微量Sc元素对5356铝合金组织和性能的影响。结果表明,在电源功率10 k W,拉坯速率8 cm/min,冷却水量1.7 m3/h的工艺条件下,5356铝合金具有最优的表面和内部质量以及综合力学性能,抗拉强度、伸长率分别可达310.0 MPa和16.3%,且铸锭表面无明显铸造缺陷,边部组织基本为等轴晶,心部组织呈破碎枝晶形态,第二相分布均匀。5356铝合金合理的均匀化处理工艺参数为440℃,30 h,空冷,均匀化处理后合金元素Mg的微观偏析基本消除,在晶界连续分布的Al8Mg5相明显回溶。微量的Sc元素显著提高5356铝合金的强度和塑性。实验证明,5356Al+0.4%Sc(质量分数)合金晶粒明显细化,第二相数量减少,抗拉强度和伸长率达330.0 MPa和29.0%,分别提高6.5%和77.9%。     

Ag/BiVO4复合纳米纤维光催化性能的研究

本文采用静电纺丝法制备了不同Ag负载含量的Ag/BiVO₄纳米纤维复合材料,并对其相结构,形貌,可见光催化性能进行了表征。结果表明,Ag的引入能够很大程度的提高复合材料的光催化效率,10%Ag负载的Ag/BiVO₄复合纳米纤维能够在可见光辐照20min内将罗丹明B完全降解。这种异质结够有利于光生电子对的分离,提高光生载流子寿命,是Ag/BiVO₄复合纳米纤维光催化性能显著提高的原因。     

高过冷度Zr-Cu-Ni-Al-Hf-Ti块体非晶合金

以Hf和Ti作为替换元素对Zr60Cu20Nil0Al10非晶合金进行了掺杂(替换法)研究．结果表明，掺杂元素含量有一最佳范围，其中，Ti的最佳含量约为2％(原子分数)左右，而Hf的最佳含量为3％．在最佳含量时二者都具有明显的扩大合金过冷温度区间ΔTx的作用．超过最佳掺杂量，会使非晶相变得不稳定，促进某些晶化相的形成，从而降低ΔTx．当采用Hf和Ti两种元素的最佳含量联合掺杂时，稳定非晶相的作用更加明显，并且ΔTx提高的幅度大于两种元素单独掺杂时的效果．ΔTx最大(144℃)的成分为：Zr60Cu20Ni8Al7Hf3Ti2，该合金Tg＝357℃，Tx＝501℃，Trg＝0．59．     

Influences of processing routine on mechanical properties and structures of 7075 aluminum alloy thick-plates

1　INTRODUCTIONAluminumalloy 70 75 ,havingsuperiormechani calpropertieswithahighspecificstrength ,isoneoftheattractiveengineeringmaterialsforapplicationinaircraftstructural partsandotherhighlystressedstructuralapplicationswhereveryhighstrengthandgoodresistancetocorrosionarerequired[1,2 ] .Itmayperform greatdifferentlywithdifferentworkprocess ing .Investigationsonthisalloyhavealwaysbeengo ingoninordertotapitslatentpowerofservice[37] .Alloying ,grainrefiningandsolution agingarethemainmethod…