Effect of AlP master alloy on grain refinement of primary silicon in eutectic Al-Si alloys

To obtain the finer primary silicon crystals, the proprietary Al-P master alloy was adopted to modify the eutectic Al-Si alloys and the most suitable modification process was made in the experiments. The SEM (Scanning Electron Microscope) and DSC (Differential Scanning Calorimeter) analysis indicate that the Al-P modifier has more advantages over Cu-P and Fe-P modifier in easily addition, no elemental alteration and less undercooling of primary silicon‘s solidification, which suggests the Al-P master alloy is an effective modifier of eutectic Al-Si alloys.     

Sr+B联合处理对Al-Si合金组织的影响

采用制备的Al-Sr-B中间合金作为晶粒细化变质剂,观察不同Sr,B含量时Al-Si合金中枝晶和共晶Si形态与大小的变化,考察了Sr,B间的交互作用。研究发现Al-Sr-B中间合金对近共晶Al-Si合金具有很好的细化变质效果。     

AI—Si合金在汽车工业中的应用前景及研究现状

AI－Si合金由于其良好的性能已在汽车工业中得到了广泛应用。为了改变共晶硅和初晶硅的形态和分布,以期得到不同性能要求的铸件,必须对AI－Si合金进行变质处理。然而,Na、Ar、P变质处理均存在不同程度的局限性,如何改进变质效果,解决已存在的问题,研究者已作了很多富有成效的工作。为了进一步扩大AI合金在汽车工业中的应用,研究者们一直在进行新型铝合金材料的研究,尤其是高硅铝合金的发展,已引起人们的广泛重视。本文对上述工作进展作一回顾。     

Al_2O_3／Al－Si合金复合材料中硅相形貌观察

利用挤压铸造制备Ａｌ２Ｏ３／Ａｌ－Ｓｉ合金复合材料，在扫描电子显微镜（ＳＥＭ）上观察了复合材料中的硅相形貌．结果表明Ａｌ２Ｏ３纤维与Ｓｉ相之间存在共格界面，可作为硅相非自发形核的衬底；复合材料中的初生硅可在纤维表面形核生长为颗粒状；复合材料中的纤维在Ａｌ－Ｓｉ共晶体的共生生长过程中，可触发孪晶，导致纤维附近的共晶硅里变质形态．     

复合变质对过共晶铝硅合金晶体形貌的影响

采用光学显微镜等手段对复合变质处理后的过共晶铝硅合金显微组织、形貌进行了分析．结果表明：硅含量为20％和25％时,经过磷和稀土复合变质后,使粗大块状、条状的初晶硅的尺寸明显减小且棱角钝化,较大针状的共晶硅变为短杆状或颗粒状,使显微组织明显细化．而磷对含硅量30％的铝硅合金的初晶硅的细化效果不是很明显．     

Effect of P/M value on the preforms and microstructures of spray formed 70Si30Al alloy

A novel 70Si30Al alloy was prepared by the spray forming process for electronic packaging materials. The effect of the ratio of atomization pressure to metal melt mass flux rate （P/M） on the preforms and microstructures of the spray-deposited 70Si30Al alloy was studied. The results indicate that the PIM value has a considerable influence on the formation of the preforms and the optimal value is in the range of 0.209-0.231 MPa/（kg.min^-1）. The microstructure of the spray formed 70Si30AI alloy is fine and homogenous. The primary silicon phases distributing in the aluminum matrix evenly are fine and irregular. The aluminum matrix is divided into two groups： supersaturated α-Al phase or α-Al phase and Al-Si pseudoeutectic phase or Al-Si eutectic phase.     

Application of CX-type modifiers in Al-Si alloys

The modification effect of CX-type (CX means the modifiers that have long effective term) modifiers applied in ZL108 and ZL104 Al-Si alloys has been studied in detail. The results show that the morphologies of the eutectic silicon and the primary silicon can be modified and refined simultaneously. The modification effect acts quickly and can maintain a period of 8 h by the CX-type modifiers. The CX-type modifiers increase the mechanical properties of Al-Si alloys and improve the service properties of machine parts made of Al-Si alloys (such as piston and cylinder etc.). In modifying processes, the amount of the addition of CX-type modifiers is smaller than that of any other modifiers, and the modifying procedures are simple. There are no smoke, no dust, and no irritant smell in modifying processes using CX-type modifiers. Therefore, the CX-type modifiers have advantages in economy and environment protection.     

A1TiCCeP对Al-30％Si合金初晶硅相的变质效果研究

借助SEM与XRD分析手段,对自制的AITiCCeP（舍2％P）中间合金进行物相分析,并以Al-30％Si合金为变质对象,探讨其对初晶硅的变质效果与变质机理。结果发现：A1TiCCeP中间合金组织中含有TiC、AlP、TiAl3和Ti2Al20等物相,当A1TiCCeP的添加量（以磷的实际添加量计算）为Al-30％Si合金质量的0．15％时,对初晶硅变质效果显著,平均尺寸约为281zm,优于商用Cu．P中间合金。     

Effects of electric pulse on microstructure of Al-Si alloy in liquid and solid states

In order to investigate the change in liquid microstructure of Al-Si alloy treated by electric pulse (EP), X-ray diffraction tests with liquid A1-Si alloy and ZL109 alloy treated or not by EP were carried out. The results show that the number of Al-Si atomic clusters decreases and that of Al-Al and Si-Si atomic clusters increases for the treated samples. The tests with ZL109 alloy indicate that a large amount of primary crystal Si appears in the solidified microstructure after treated by EP. It is found that EP can change the microstructure of liquid metal by affecting the probability of electrons appearing in different atoms (Al and Si) in the liquid metal.The combining force of different atoms decreases relatively, and that of the same atoms increases, which is the main reason of re-ducing the atomic cluster with different atoms (Al-Si) and increasing the atomic cluster with the same atoms (Al-Al, Si-Si). The in-creasing of the atomic cluster with the same atom cluster resulted in the increasing of Si activity and the higher point of eutectics in the phase diagram. It makes a lot of primary silicon appeared in ZL109 alloy.     

铝硅合金潜热变化规律的DSC分析

通过真空电弧炉制备不同Si质量分数的铝硅合金,利用差示扫描量热分析仪测量合金的潜热,分析了Al-Si合金的成分与潜热之间的相互关系。结果表明,Al-Si合金初生相和共晶相的潜热需要进行单独求解,在Si的质量分数为4.16％～21.4％范围内,Al-Si合金潜热随Si的质量分数增加呈线性增加,亚共晶潜热、过共晶潜热具有不同的线性关系,分别为:L_hypo=353.4+12X(亚共晶)和L_hyper=409.6+7.54X (过共晶),其中X为Si的质量分数;过共晶Al-Si合金中初生Si相的潜热与纯Si的潜热相差较大是由Al-Si熔体中与纯Si熔体中Si的形态差异引起的。     

Ce在铝硅合金中的显微分布研究

用涂敷法自射线照相法研究了Ce在铝硅合金中的分布。结果表明,Ce在初生α-Al和多数初生Si中是贫化的,Ce主要富集于共晶体中。共晶Si中的含Ce量远多于共晶α-Al中的含Ce量。     

Characterization by EBSD of antimony-calcium rich phases formed during purification of aluminum scrap

We studied the influence of antimony on the modification rate of the silicon eutectic with sodium and/or strontium for casting of Al-Si alloys, and introduced controlled Ca and Sb to the system and studied the resulting compounds, which were determined to be Ca₂Sb and AlSb. Scanning electron microscopy together with the complementary technique of electron backscatter diffraction (EBSD) were used to characterize the materials. The experimental results provided the basis for us to establish that antimony removal from Al occurs mainly through the reaction (Sb)Al + 2Ca = Ca₂Sb + Al.     

三元Pb-Sb-Sn合金的快速凝固及组织特征

实现了三元Pb-12%Sb-4%Sn和Pb-15%Sb-10%Sn合金在深过冷条件下的快速凝固,实验中获得的最大过冷度分别为65 K(0.13TE)和70 K(0.13TL)。XRD分析表明,这两种合金在实验过冷度范围内均由(Pb)固溶体、(Sb)固溶体和SbSn金属间化合物三相组成。在小过冷条件下,Pb-12%Sb-4%Sn共晶合金的三相以层片状交替分布,协同生长。随着过冷度增大,(Sb)作为初生相以小平面方式生长,且三元层片共晶组织显著细化。对于Pb-15%Sb-10%Sn合金,其凝固组织由初生相、二相共晶和三元共晶组成,初生SbSn相以具有小平面特征的枝晶方式生长。在实验基础上,对三元Pb-Sb-Sn合金的形核特征和生长规律进行了理论分析。     

氢对铝-硅合金变质作用的影响初探

本文通过铝-硅共晶合金在不同氢含量下,用等量富铈混合稀土变质处理时,发现变质效果受氢的影响很大。合金的变质效果与氢含量之间的关系符合具有最大值的抛物线分布。即氢含量低时,变质不良;氢含量高时,基本上失去了变质效果;而氢含量处于中间的某一值时,具有最佳的变质效果。在此实验结果的基础上,进行了简单的分析。这项工作还有待进一步在氢对变质影响的机理方面做深入细致的工作。     

熔体温度处理对磷铜变质Al-20%Si组织的影响

研究熔体温度处理工艺（包括熔体混合及熔体过热处理）与磷铜变质对Al-20%Si合金中硅相形态的影响。结果表明：在本试验条件下,单纯添加磷铜变质剂的Al-20%Si合金,当添加其合金质量的0.4%时,初晶硅由未变质前的97μm减小到65μm,减小了33%;当将熔体温度处理工艺与磷变质处理相结合时,此时Al-20%Si合金中的初晶硅尺寸减小至36μm,减小了62%,且钝化现象显著,弥散分布于α-Al基体上,共晶硅也由未变质前的长针状变为短纤维状和点状。     

Investigation of microgravity effect on solidification of medium-low-melting-point alloy by drop tube experiment

The solidification microstructure of Al-Ni, Al-Cu, Ag-Cu, Al-Pb and Cu-Co alloys quenched in silicone oil before and after free fall in evacuated 50 m drop tube were investigated contrastively. The effect of microgravity on the solidification process of medium-low-melting-point eutectic, monotectic and peritectic alloys were analyzed and discussed. The results indicated that the effects of microgravity on the eutectic cell shape, the pattern in eutectic cell and the inter-eutectic spacing were different for different types of eutectic systems; the size distribution of Pb particles in Al-5wt% Pb monotectic alloy was significantly changed by microgravity; and the shape of retained primary α-Co phase in Cu-10wt%Co peritectic alloy was also changed by microgravity. These results are beneficial for people to further identify and analyze the solidification behavior of multiphase alloys under microgravity.     

石墨铝复合材料的研制及摩擦磨损

本文叙述了一种制备共晶型铝硅合金-石墨颗粒复合材料的方法,即采用盐溶液对石墨颗粒进行预处理。通过液体旋涡技术将石墨颗粒加入到共晶型铝硅合金中;对石墨铝复合材料在无润滑条件下的磨损特性进行了研究,探讨了法向载荷、滑动速度及复合材料中的石墨含量对石墨铝复合材料摩擦系数和磨损速率的影响。     

用熔剂法改善铸造铝硅合金组织和性能

本文介绍用XF－5型熔剂改善铸造铝硅合金组织和性能的试验研究结果，获得了硅晶体呈细小颗粒状、α相细化且均匀分布以及化合物相被打碎且弥散分布的铸态最佳组织，并显著减少合金气缩松倾向，增加合金流动性，有效地除气、除渣，从而使合金性能得到明显提高，铸件合格率上升。     

EET research on the Al-22%Si alloy under the action of electric pulses

Based on the empirical electron theory of solids and molecules (EET), the phase valence electron structure parameters of Al-22%Si alloy are calculated, and the sensitivity of the bond network of Al-Si alloy melt to temperature (energy) and the effect of the sensitivity on the morphology are studied. The results show that the Si-Si clusters with larger n _A in the slightly superheated Al-Si alloy melt supply the nucleation core to the primary silicon phase in the hypereutectic Al-22%Si alloy, and strongly generate the drag-like effect for the Al-Si clusters around them; that the variation of temperature significantly affects the stability of bonds of the core so that the solidified structure is changed; that the electric pulse applied to the alloy melt can irrecoverably alter the stability of Si-Si clusters, then the modification of the solidified structure morphology of alloys is generated; that the higher the energy of the electric pulse, the less stable the Si-Si clusters, and the more significant the electric pulse modification. Supported by the National Natural Science Foundation of China (Grant No. 50674054), and the College Key Laboratory Open Fund of Liaoning Province(Grant No. 200516203)     

Al-Si合金回转件车削表面雪花斑形成机理

Al-Si合金回转件车削加工时,工件表面会产生明暗相间的雪花斑,影响工件使用性能.为了找到雪花斑产生的机理,针对ZL101铸件加工表面进行了粗糙度测量,并对工件有雪花斑和无雪花斑位置进行了力学性能测试和微观组织观察.结果表明:车削工件表面有雪花斑位置的粗糙度显著大于无雪花斑位置的粗糙度;该位置取样样品的强度小于无雪花斑位置取样样品的强度.微观组织观察表明,有雪花斑位置样品的α-Al相晶粒尺寸和枝晶间距显著大于无雪花斑的,且该位置共晶组织中的硅相颗粒尺寸及共晶组织所占比例均大于无雪花斑的.组织粗大和共晶组织的增加促使Al-Si合金切削加工过程中切削表面雪花斑的形成.