Modeling and optimizing of steel and mushy Al-28Pb alloy bonding

1　ＩＮＴＲＯＤＵＣＴＩＯＮＡｔｐｒｅｓｅｎｔ,ｔｈｅｔｙｐｉｃａｌｍａｔｅｒｉａｌｏｆｎｅｏｔｙｐｅｂｅａｒ ｉｎｇｉｓｓｔｅｅｌ ｂａｃｋｅｄＡｌ 2 0Ｓｎａｌｌｏｙｂｏｎｄｉｎｇ ｐｌａｔｅ[1 ] .Ｆｏｒｓｔｅｅｌ ｂａｃｋｅｄＡｌ 2 0Ｓｎａｌｌｏｙｂｏｎｄｉｎｇｐｌａｔｅ ,ｓｔｅｅｌｂａｃｋｈａｓｈｉｇｈｓｔｒｅｎｇｔｈｗｈｉｃｈｃａｎｂｅａｒｔｈｅｅｘｔｅｒｎａｌｌｏａｄ ,ａｎｄＡｌ 2 0ＳｎａｌｌｏｙｌａｙｅｒｉｓａｌｕｂｒｉｃａｔｉｎｇｏｎｅｉｎｗｈｉｃｈＡｌｓｕｂｓｔｒａｔｅｈａｓｅｘｃｅｌ…     

Relationship between solid fraction of slurry and property of steel/mushy Al-20Sn semi-solid bonding

The slurry of Al-20Sn alloy was prepared using electromagnetic-mechanical stirring method.The bonding of steel/mushy Al-20Sn was conducted using casting rolling technique.The bonding parameters were 505℃ for preheat temperature of steel plate and 10mm/s for rolling speed.The interfacial mechanical property and structure of steel/mushy Al-20Sn bonding plate were studied.The results show that the relationship between solid fraction of Al-20Sn slurry and interfacial shear strength of bonding plate is S=52.9 0.998ψs-0.0144ψs^2(where S is interfacial shear strength,ψs is solid fraction.)The largest interfacial shear strength is 70.2MPa when solid fraction is 34.6%.The interface of bonding plate is made up of Fe-Al compound and Fe-Al solid solution alternatively.     

快速凝固Al-Pb合金的显微组织

采用单辊旋铸法分别制备了Al-5%Pb, Al-8%Pb和Al-15%Pb三种合金条带, 并利用TEM分析其显微组织. 结果表明 在快速凝固下, Al-Pb合金中的第二相(f.c.c. Pb)在基体中分布均匀, Pb颗粒尺寸随Pb含量增加而增加, 随冷却速度的增大而减小, Pb颗粒的尺寸呈双峰或三峰分布特征. 此外, 还分析了快速凝固下偏晶合金的凝固过程, 对上述现象进行了解释.     

颗粒成形Al-Pb合金板材的微观结构与力学性能

研究了Al-8Pb-3Si-2Sn-1Cu(质量分数, %)合金的颗粒在挤压轧制成形时, 合金的微观结构与性能. 结果显示 Al-Pb合金颗粒中Pb分布在枝晶间隙或"嵌"在基体中; Al-Pb合金颗粒经挤压轧制及随后的退火, 合金板材中低熔点Pb, Sn第二相均匀地呈球形分布; 合金强度(σb)可达95.8MPa, 延伸率(δ)可达16.3%; 在变形过程中, Al-Pb合金颗粒的新生表面层中低熔点Pb, Sn第二相的重新分布影响材料的强度与延伸率.     

Interfacial bonding strength of Al-Pb bearing alloy strips and hot dip aluminized steel sheets by hot rolling

1　ＩＮＴＲＯＤＵＣＴＩＯＮＡｌ Ｐｂａｌｌｏｙｓａｓａｎｅｗｌｙｄｅｖｅｌｏｐｅｄｂｅａｒｉｎｇｍａｔｅ ｒｉａｌｆｏｒａｕｔｏｍｏｂｉｌｅｓｈａｖｅａｔｔｒａｃｔｅｄｌｏｔｏｆａｔｔｅｎｔｉｏｎｄｕｅｔｏｔｈｅｉｒｏｕｔｓｔａｎｄｉｎｇ ｐｒｏｐｅｒｔｉｅｓｓｕｃｈａｓｗｅａｒｒｅｓｉｓ ｔａｎｃｅ ,ａｎｔｉ ｓｅｉｚｕｒｅ,ｃｏｍｐａｔｉｂｉｌｉｔｙ ,ｆａｔｉｇｕｅｒｅｓｉｓｔａｎｃｅａｎｄｌｏｗ ｐｒｉｃｅ[1～ 4].Ｈｏｗｅｖｅｒ ,ｔｈｅｆａｂｒｉｃａｔｉｏｎｏｆａｓ ｃａｓｔＡｌ Ｐｂａｌｌｏｙ …     

铝合金半固态浆料中球形颗粒的演变

用AlSi7Mg0.6半固态浆料进行实验,研究球形颗粒的演变机理.在略高于液相线温度下水淬的样品中结晶相主要为枝晶,而采用旋转圆筒的方式来搅拌熔体使其冷却到半固态温度范围内时样品的结晶相完全球化.在铸造前进行较长时间的内冷却和搅拌,可以得到较高的固相分数.不同大小的枝晶碎片的存在表明,在搅拌过程中,初始的固相分数形成后不再受冷却的影响.     

铝合金半固态加工技术应用

对于垂直式电磁搅拌器 ,提高搅拌效率的最有效措施是减少漏磁通。对于通常的Al Si类合金的半固态加工坯料 ,在足够的搅拌强度下 ,熔体冷却速度控制在 0 .5～ 3.0℃ /s可得到较好的组织。在二次加热时共晶体中的针簇状Si相通过扩散溶解到α相中 ,Si相本身变成细小颗粒 ,初生α相在共晶熔化后才开始球化。对于AlSi9Cu3合金 ,其共晶相在二次加热熔化后重新凝固时 ,Si相呈细小颗粒析出 ;对于A357合金 ,仍然生成针簇状组织。与常规压铸相比 ,半固态压铸内浇道厚度要增加 2～ 3mm ,压射比压要高 5～ 2 0MPa,才能保证充型完好。     

Effect of SiC volume fraction on the age-hardening behavior in SiC particulate-reinforced 6061 aluminum alloy composites

The age-hardening behavior in the SiC particulate-reinforced 6061 aluminum alloy composites (SiCp/6061 Al alloy composites) was investigated using hardness measurement, calorimetric technique and transmission electron microscopy. The aging time for the peak hardness in 10%SiCp/6061 Al and 20%SiCp/6061 Al alloy composites was shorter than that of the unreinforced 6061 Al alloy, and the age-hardening was most accelerated in the 20%SiCp/6061 Al alloy composite. It is induced from the high density of dislocations in SiCp/6061 Al alloy composites which act as heterogeneous nucleation sites of precipitates and as a high diffusivity path of alloy elements. The precipitation sequence and the aspect of precipitates in the 6061 Al alloy cannot be affected considerably by the presence of SiC particulate and the volume fraction of SiC particulate. The activation energies for the formation of the intermediate β' phase in the unreinforced 6061 Al alloy, 10%SiCp/6061 Al and 20%SiCp/6061 Al alloy composite were 142.6 kJ/mol, 127.3 kJ/mol, 106.1 kJ/mol, respectively.     

Determination of latent heat and changes in solid fraction during solidification of Al-Si alloys by the CA-CCA method

Effects of Si content and the presence of various minor elements, e.g. Mg, Ti, Sr and P, on the latent heat of Al-Si alloys have been analysed by the CA-CCA method. The results indicate that the latent heat of Al-Si alloys increases with increasing Si content. For hypo-eutectic and eutectic alloys, Sr-modified and Ti-grain refined alloys release more latent heat than non-treated alloys. However, for hyper-eutectic alloys, the latent heat values are lower for P-refined and Ti-grain refined alloys than for non-treated alloys. In addition, the introduction of Mg into Al-Si alloys increases the latent heat. Linear and higher order regression formulae for fitting the latent heat with Si content have been obtained in this study. The results of the measured latent heat through both the CA-CCA method and the DTA method and the theoretical latent heat values calculated by the simple mixture rule have been compared.

Furthermore, the changes in solid fraction during solidification of Al-Si alloys with various compositions have also been determined by the CA-CCA method by taking into account the difference in latent heat between the Al and Si phases. Finally, the fluidity lengths of Al-Si(Mg) alloys have been related to latent heat, percent eutectic and superheat.     

Effect of solid fraction on steel-mushy Cu-graphite pressing bonding

The pressing bonding of steel plate to QTi3.5-3.5graphite slurry was studied. The bonding conditions were 620℃ for preheating temperature of steel plate, 530℃ for preheating temperature of dies, 50 MPa for pressure and 2 min for pressing time. The relationship between the solid fraction of QTi3.5-3.5graphite slurry and the interracial mechanical property of bonding plate was obtained. The results show that when the solid fraction of QTi3.5-3.5graphite slurry is smaller than 45.8%, the interracial shear strength of bonding plate increases with the increasing of solid fraction. When the solid fraction is larger than 45.8%, the interracial shear strength decreases with the increasing of solid fraction. When the solid fraction is 45.8%, the largest interracial shear strength of bonding plate 127 MPa can be got, and the interface is made up of Fe-Cu solid solution.     

Conception of tooling adapted to thixoforging of high solid fraction hot-crack-sensitive aluminium alloys

Thixoforging is a type of semi-solid metal processing at high solid fraction (0.7<?_s<1), which involves the processing of alloys in the semi-solid state. Tooling has to be adapted to this particular process to benefit shear thinning and thixotropic behaviour of such semi-solid material. Tooling parameters, such as the forming speed and tool temperature, have to be accurately controlled because of their influence on thermal exchanges between material flow and tool. These thermal exchanges influence the high-cracking tendency and the rheology of the semi-solid material during forming, which affects parts properties and therefore their quality. Extrusion tests show how thermal exchanges influence quality of thixoforged parts made of 7075 aluminium alloys at high solid fraction by modifying process parameters like forming speed, tool temperature and tool thermal protector. Thus an optimum in terms of thermal exchanges has to be found between surface quality and mechanical properties of the part. A direct application is the evaluation of surface quality of thixoforged thin wall parts made of 7075 aluminium alloy.     

6061铝合金半固态浆料的行波电磁搅拌制备工艺

采用低过热度浇注和弱行波电磁搅拌工艺,成功制备出6061铝合金半固态浆料。研究了浇注温度、搅拌功率和搅拌时间对6061铝合金半固态浆料的影响。结果表明:低过热度浇注和弱行波电磁搅拌技术可获得具有良好球状初生α-Al的6061合金半固态组织。浇注温度接近液相线温度,搅拌功率大于2.5kW,搅拌时间大于10s时,6061铝合金半固态浆料中的初生α-Al细小圆整,尺寸均匀。但是当浇注温度降至液相线温度时,组织中出现少量树枝晶。最佳工艺参数:浇注温度667℃、搅拌功率2.5kW、搅拌时间10s。     

离心铸造Al-Fe合金凝固过程中的固相迁移运动

离心铸造Ａｌ－Ｆｅ合金凝固过程中的先析出相与合金液之间具有较大的密度差,在离心力场作用下,先析出相将沿径向由内向外迁移,致使初生相沿铸件向呈梯分布,根据离心铸造Ａｌ－Ｆｅ合金过程中固相迁移运动的特点,建立了描述这一运动过程的数学模型,并提出采用求平均速度的方法对固相迁移速度进行数值求解,求出了凝固过程中时刻固相迁移运动速度的分布情况,揭示了离心铸造Ａｌ－Ｆｅ合金过程中的固相迁移运动规律 。     

Al—Si系合金制备工艺与微观组织的关系

分别采用双级雾化、超音气体雾化、喷射沉积和金属型铸造等工艺制备了Ａｌ－２０Ｓｉ和２０２４－２０Ｓｉ－５Ｆｅ 合金。利用ＸＲＤ、ＴＥＭ 和ＳＥＭ 测试技术分析了制备工艺对合金相组成、α－Ａｌ相晶格常数和固溶度的影响。结果表明：当制备工艺的冷却速度达到１０３ Ｋ／ｓ 以上时,β－（Ｆｅ２Ｓｉ２Ａｌ９）、ＣｕＡｌ２ 和Ｍｇ２Ｓｉ相的析出得到有效抑制;第二相随制备工艺的冷却速度增大而细化,α－Ａｌ相的晶格常数减小;Ａｌ－２０Ｓｉ合金中硅元素在α－Ａｌ中的最大固溶度高达３．２０９％ 。     

Effects of solid deformation and melt vibration on structure and refining performance of Al5Ti1B master alloy

1　ＩＮＴＲＯＤＵＣＴＩＯＮＧｒａｉｎｒｅｆｉｎｅｍｅｎｔｏｆｆｅｒｓｓｕｂｓｔａｎｔｉａｌｂｅｎｅｆｉｔｓｉｎｂｏｔｈｃｏｎｔｉｎｕｏｕｓｃａｓｔｉｎｇｂｙｄｉｒｅｃｔｃｈｉｌｌ (ＤＣ)ａｎｄｉｎｃａｓｔ ｔｏ ｓｈａｐｅｐｒｏｄｕｃｔｓ[1].Ａｌ 5%Ｔｉ 1 %Ｂｍａｓｔｅｒａｌ ｌｏｙ ,ｗｈｉｃｈｍａｉｎｌｙｃｏｎｔａｉｎｓＴｉＡｌ3ａｎｄＴｉＢ2 ｐａｒｔｉｃｌｅｓｉｎＡｌｍａｔｒｉｘ[2 ,3]ｈａｓｂｅｅｎｐｒｏｖｅｎｔｏｇｉｖｅｔｈｅｂｅｓｔｇｒａｉｎｒｅｆｉｎｅｍｅｎｔ[4 ,5 ].Ａｄｄｉｔｉｏｎｏｆ 0 …     

机械合金化过程中Al-Pb相变的热力学和动力学研究

将Al、Pb粉末按照Al 2 2 5Pb(at% ,下同 )的配比进行了机械合金化 ,并对Al Pb合金的物相、晶粒尺寸、点阵常数作了测定和分析。结果表明 ,机械合金化可以获得Al Pb纳米晶超饱和固溶体。参照Miedema半经验理论模型 ,计算了该合金系的相变驱动力 ,分析指出当Pb含量为 86 8%～ 98 4 %时 ,该合金系存在发生非晶的化学驱动力。利用机械合金化动力学机制分析了Al Pb形成过饱和固溶体和非晶的可能性 ,其中Al 2 2 5Pb形成固溶体的自由能要低于形成非晶的自由能 ,但都大于零     

固态回收法制备Mg-Zn-Y-Zr合金的微观组织和力学性能

采用冷压法压实Mg-Zn-Y-Zr合金碎屑,在不同温度和不同挤压比下进行热挤压。结果表明：在低于320℃时挤压,微观组织由大量再结晶晶粒和少量未再结晶晶粒组成,合金具有较高的强度和较低的韧性;当挤压温度升高到360℃时,发生完全再结晶,微观组织由等轴晶组成,合金具有较低的强度和较高的韧性;当挤压温度升高到420℃时,微观组织由粗大的等轴晶组成,导致了合金的力学性能下降;当挤压比从8增加到16时,晶粒明显细化,力学性能显著提高,然而,随着挤压比的进一步增加,屈服强度和极限抗拉强度升高幅度不大。     

Effects of casting speed on microstructure and segregation of electromagnetically stirred Aluminum alloy in continuous casting process

Recently, a semi-solid metal processing has been acknowledged as a cost-effective technique to be able to manufacture high quality product for the transportation industry.In this study a hypo-eutectic Al alloy was fabricated by means of an electromagnetic stirrer in continuous casting process and the microstructural change during solidification due to a fluid flow by electromagnetic stirring was examined.Due to the forced fluid flow during solidification a dendritic phase of primary α phase of Al alloy was turned into a globular phase, which can make the Al alloy get a thixotropic behavior in the semi-solid region.In order to establish the quantitative relationship between microstructure and the process parameters, the morphology shape, a silicon distribution and a size of primary α phase were observed according to casting speed in continuous casting machine.The primary α phase was turned into the degenerate dendrites approaching a spherical configuration with increasing casting speed.The fine-grained and equiaxed microstructure appeared at higher casting speed.A segregation behavior of Si element was declined with increasing casting speed and a very uniform distribution of Si element was observed on the billet at a casting speed of 600 mm·min-1.A thickness of the solidifying shell of the billet was shortened with increasing the casting speed.     

Simulation study on distribution of void fraction in copper converter bath

1　ＩＮＴＲＯＤＵＣＴＩＯＮＴｈｅｄｉｓｔｒｉｂｕｔｉｏｎｃｈａｒａｃｔｅｒｉｓｔｉｃｓｏｆｖｏｉｄｆｒａｃｔｉｏｎ ,ｂｕｂｂｌｅｓｉｚｅ ,ｂｕｂｂｌｅｖｅｌｏｃｉｔｙｉｎｔｈｅｍｏｌｔｅｎｂａｔｈｏｆａｍｅｔａｌｌｕｒｇｉｃａｌｒｅａｃｔｏｒ ｐｌａｙａｎｉｍｐｏｒｔａｎｔｒｏｌｅｉｎｔｈｅｐｒｏｃｅｓｓｋｉｎｅｔｉｃｓ .Ａｇｒｅａｔｎｕｍｂｅｒｏｆｅｘｐｅｒｉｍｅｎｔａｌｓｔｕｄｉｅｓｈａｖｅｂｅｅｎｃａｒｒｉｅｄｏｕｔｔｏｓｔｕｄｙｔｈｅ ｐｈｙｓｉｃａｌｃｈａｒａｃｔｅｒｉｓｔｉｃｓｏｆ ｇ…     

高能球磨制备的Al-Pb纳米相复合结构合金中纳米相Pb的体积分数对其长大行为的影响

利用X射线衍射仪、扫描电子显微镜和透射电子显微镜研究了高能球磨制备的Al-Pb纳米相复合结构合金中纳米相Pb的体积分数对其长大行为的影响。结果表明尽管Al-Pb纳米相复合结构中组成相的尺寸均在纳米量级,不同体积分数的纳米相Pb的长大行为均遵循三次方定律。纳米相Pb的粗化速率随其体积分数的增加而增加,增加幅度大于理论在此成分范围内的预测。纳米相Pb的粗化激活能不随合金成分而变化。纳米相Pb的粗化受溶质原子沿溶剂基体的晶界扩散所控制。