超声振动对Al-17Si-xFe合金富铁相形貌的影响

用直接超声振动法处理了Al-17Si-xFe(x=2,3,4,5,质量分数)合金,利用光学显微镜、XRD及EDS等手段分析了传统铸造工艺和超声半固态成形合金的微观组织。结果表明,在无超声振动时,Fe含量为2%的铸态合金组织中的富Fe相以长针状β-Al5FeSi相为主,伴有少量板条状δ-Al4FeSi2相。随着Fe含量的增加,合金组织中长针状β-Al5FeSi相逐渐减少,针片状δ-Al4FeSi2相逐渐增多,Fe含量为5%时以粗大针片状δ-Al4FeSi2相为主。在液相线附近对上述不同Fe含量的合金熔体施加一定时间的超声振动后浇注到金属型,富Fe相均以块状和短条状δ-Al4FeSi2相为主,其晶粒平均等效直径在18～46μm之间,明显细化,此外还伴有少量针状β-Al5FeSi相。初步探讨了超声振动影响富Fe相形貌的作用机理。     

时效处理对AlSi9Cu3压铸铝合金组织和力学性能的影响

通过拉伸试验、光学显微镜、扫描电镜及能谱仪等分析手段研究了T5时效处理(160 ℃×6 h)后AlSi9Cu3高压铸造(HPDC)铝合金的显微组织、力学性能和拉伸断口形貌。结果表明,AlSi9Cu3高压铸造铝合金试样经过时效处理后,显微组织主要为等轴晶状的初生α-Al、共晶Si相以及析出θ-Al₂Cu相和α-Fe相。析出的平衡相θ-Al₂Cu弥散分布在晶界上,提高了AlSi9Cu3压铸铝合金的强度和硬度。时效处理后,AlSi9Cu3压铸铝合金的抗拉强度、屈服强度、伸长率和硬度分别为375 MPa、258 MPa、4.0%和94 HBW。同时在AlSi9Cu3压铸铝合金的拉伸断口观察到了准解理和少量沿晶断裂特征。     

Effect of heat treatment on microstructures and mechanical properties of A356 alloy cast through rapid slurry formation (RSF) process

The effect of T5 heat treatment on microstructure and mechanical properties of A356 alloy was observed. The as-cast A356 alloy exhibited coarse dendrites and long Si needles. RSF process changed the dendritic α-Al phase to globular morphology which helps in improving the mechanical properties of the alloy. The addition of 0.6wt-% Al–5Ti–1B grain refiner refined the average grain size of primary α-Al phase. T5 heat treatment at 170 °C for 20 h in different processing conditions was given to A356 alloy. T5 heat treatment led to further refinement of α-Al phase and Si needles, precipitation hardening due to Mg₂Si phase and reduction in the porosity level (%). The Quality Index for A356 alloy in different processing conditions was also measured. Results showed that RSF process with the use of baffles, addition of grain refiner and T5 heat treatment had improved the mechanical properties over other processing conditions.     

Al_(80)Ni_6Y_8Co_4Cu_2 GLASS ALLOYS CONTAINING NANOSCALE PARTICLES BY ISOTHERMAL ANNEALING OR QUENCHING

1. IntroductionPartial nanocrystalline Al-rich glajssy alloys have attracted great attention as a newmaterial because their specific strength are much higher than that of the fully amorphousAl-rich alloys and the conventional crystalline Al-based alloy[1,2]. Kim et al.I2] and Chenet al.13] reported that the values of fracture strength are above 1000MPa for Al-rich alloyswith mixed structure of nanoscale or-Al particles embedded on the amorphous matrix afterpartial crystallization. However,…     

Al-4.5Cu-3.5Zn-0.5Mg铸造铝合金的均匀化工艺及组织演变

对Al-4.5Cu-3.5Zn-0.5Mg铸态合金进行不同双级均匀化处理,采用扫描电镜、电子探针显微分析仪、差示扫描量热仪和光学显微镜等,研究了该合金的铸态组织及其在均匀化过程中的组织演变。结果表明:铸态组织主要由α-Al、粗大Al₂Cu相以及少量AlZnMgCu、Al₇Cu₂Fe相组成,合金元素枝晶偏析严重。经470 ℃×12 h均匀化处理后,AlZnMgCu相已基本回溶至基体;第二级均匀化温度由490 ℃逐渐升高到520 ℃或者延长保温时间,Al₂Cu相逐渐回溶至基体,合金元素分布趋于均匀。合金过烧温度为520 ℃,最佳双级均匀化制度为470 ℃×12 h+510 ℃×32 h,该制度与均匀化动力学计算结果基本一致。     

时效处理对7022铝合金组织与弯曲性能的影响

采用扫描电镜(SEM)、能谱分析(EDS)、X射线衍射(XRD)、电子背散射衍射(EBSD)、拉伸和弯曲试验等研究了时效处理对7022铝合金组织及弯曲性能的影响。结果表明,固溶处理后7022铝合金基体中依然含有大量黑色不溶第二相,且这些相主要由α-Al、MgZn₂、Al₂CuMg和Al₇Cu₂Fe相组成。随着时效的进行,Al₂CuMg和Al₇Cu₂Fe相逐渐溶解,与MgZn₂相性质相似的Mg(Zn, Cu, Al)₂相析出,同时晶粒逐渐长大,产生明显的析出强化效应。试样的抗弯强度主要受到第二相颗粒的数目、尺寸以及晶粒尺寸的影响。110 ℃×10 h时效条件下,合金拥有弥散分布的细小第二相颗粒和合适的晶粒尺寸,具有较好的抗弯强度和抗拉强度,其数值分别为21.7 MPa、608 MPa。     

Al-Cu-Ce合金的微观组织与力学性能

采用X射线衍射、金相显微镜、扫描电镜、能谱分析及拉伸性能测试等方法,研究3种成分Al-Cu-Ce合金的显微组织与力学性能。结果表明:铸态Al-14Cu-7Ce合金由α-Al+Al8CeCu4片状共晶组成,而Al-10Cu-5Ce、Al-18Cu-9Ce合金中除含有α-Al+Al8CeCu4共晶组织外,还分别含有α-Al和Al8CeCu4初生相。铸态Al-14Cu-7Ce合金具有优良耐热性能,即使550℃×3 h退火后仍能保持约360 MPa的抗拉强度,退火导致合金强度下降的主要原因是高温下共晶Al8CeCu4相的球化。经充分球化退火后,Al-Cu-Ce合金能获得良好的热轧、冷轧变形能力,并且变形态合金也具有良好的耐热性能,因而Al-Cu-Ce合金有望成为一种兼具铸造和变形两用的新型耐热铝合金。     

Influence of the microstructure on the machinability of heat-treated Al–10.8% Si cast alloys: Role of copper-rich intermetallics

This study was conducted with the intention of investigating a new experimental alloy, namely the 396 alloy which belongs to the Al–Si near-eutectic cast alloy group and contains about 10.8%Si. In the light of the above, the main purpose of the work is to report on the changes observed in the mechanical and machinability criteria resulting from the effects of the presence of two levels of Cu, namely 2.25% and 3.5%; and of the effects of two levels of Mg, namely 0.3% and 0.6%. In addition to the preceding, the effects of Mg-free alloys and Sr-modification on these same alloys were also investigated.The results demonstrate that the increase in the levels of Cu and/or Mg in the 396-T6 alloy has a detrimental effect on drill life. Such an effect may be attributed to the formation of large amounts of the coarse blocklike Al₂Cu phase, together with the formation of thick plates of the Al–Si–Cu–Mg phase. The Mg-free experimental alloy displays the lowest cutting force and moment in addition to producing the highest number of holes in the alloys studied. This observation may be explained by the cooperative precipitation of the Al₂Cu, Mg₂Si, Al₂CuMg, and Al₅Si₆Cu₂Mg₈ hardening phases in Mg-containing alloys which confer greater strength on the alloy than would be the case with the precipitation of only the Al₂Cu phase in the Mg-free alloy. A comparison of the non-modified alloy and the Sr-modified alloy (containing the same level of Mg and Cu additions) in terms of the number of holes drilled, reveals that the morphology of Si particles has a noticeable effect in governing the tool life of near-eutectic Al–Si alloys. The chip breakability of the alloys containing the Al₂Cu phase is superior to that of the alloys containing Mg₂Si. Thus, combined additions of Cu and Mg are expected to further refine the size of the chips produced.     

不同合金元素对Mg15Al高铝镁合金组织与性能的影响

研究了不同合金元素（Zn,Nd,Si）对Mg15Al镁合金的组织和性能的影响。通过对Mg15Al,Mg15Al1Zn,Mg15Al1Si,Mg15Al1．5Nd四种合金微观组织的观察和力学性能的测定,发现添加了合金元素后Mg合金组织中α—Mg基体和β—Mg17Al12相都得到了不同程度的细化,其中Mg15Al1Si,Mg15Al1．5Nd合金组织中有第三相生成,其形态分别为汉字状、块状,长针状。试验结果表明：添加zn和Nd元素后,抗拉强度比Mg15Al合金显著提高。提高幅度分另4为：13．2％和16．6％,而添加si元素后Mg15Al1Si合金抗拉强度比Mg15Al合金低。添加Nd元素后,伸长率比Mgl5Al合金显著提高,增幅为140％,添加了Si元素和Zn元素后,伸长率比Mg15Al合金低。     

Microstructural characterization of in situ TiC/Al and TiC/Al–20Si–5Fe–3Cu–1Mg composites prepared by spray deposition

An innovative spray-deposition technique has been applied to produce in situ TiC/Al and TiC/Al–20Si–5Fe–3Cu–1Mg composites. This technique provides a new route to solve the problems of losses and agglomeration of the reinforcement particles when they are injected into the spray cone of molten droplets during spray forming process. Experimental results have shown that the presence of needle-like Al₃Ti and Al–Si–Fe compounds, which are detrimental not only to the fracture toughness, but also to the stability of the microstructure, can be eliminated completely from the final product by using a proper Ti:C molar ratio of 1:1.3 in the Ti–C–Al preforms and adding 5 wt% TiC particles to Al–20Si–5Fe–3Cu–1Mg alloy. Moreover, another major problem of coarsening of silicon particles usually encountered in the hypereutectic Al–Si alloys has also been solved by the technique. The silicon particles in the spray-deposited 5 wt% TiC/Al–20Si–5Fe–3Cu–1Mg composite were much refined (∼2 μm) compared to those (∼5 μm) obtained in the matrix alloy without TiC addition. The formation and elimination mechanisms of Al₃Ti phase in TiC/Al composites can be explained based on thermodynamic theory. The modification of the microstructures in the spray-deposited Al–20Si–5Fe–3Cu–1Mg alloy can be interpreted in the light of the knowledge of atomic diffusion. The experimental results also showed that the ultimate tensile strength of the TiC/Al composites was improved over that of the unreinforced Al matrix.     

镁硅质量比对Al-Mg-Si合金组织、热学和力学性能的影响

以Al-Mg-Si(6XXX)系合金为基础,通过改变Mg、Si质量比,采用金属型铸造研究不同w(Mg)/w(Si)对合金的组织、热导率及力学性能的影响。结果表明,当w(Mg)/w(Si)小于1.53时,合金中的相组成主要为共晶Si、α-Al和β-Mg₂Si相;当w(Mg)/w(Si)为1.53时,合金中出现θ-Al2Cu相,而共晶Si相消失;当w(Mg)/w(Si)大于1.53时,合金中出现新相S-Al2CuMg相,而θ相逐渐减小最后消失;当w(Mg)/w(Si)为1.53时,合金具有最佳的综合性能,其热导率为175.5 W/(m·K),抗拉强度为153 MPa,硬度(HV)为109.14,伸长率为6.54%。     

Mechanism of Exfoliation (Layer Corrosion) of AI-5%Zn-1%Mg

Abstract

The mechanism of exfoliation in AlZn5Mg1 alloy has been studied by making a survey of the phasesb occurring in the alloy in the naturally aged and artificially aged conditions, preparing the phases in pure state and investigating their electrochemical properties. It has beenfound that in the naturally aged alloy, the attack is confined to lamellar zones in the structure giving rise to the exfoliation. Finely dispersed α-Al(Fe, Me)Si phase particles arranged in streaks along the extrusion or rolling direction act as cathodes and the anodic areas consist of narrow zones of the Zn- and Mg-rich matrix, next to the particles. Between the streaks of α-Al(Fe,Me)Si particles, layers of matrix are left unattacked. Since the main factor determining the amount of α-Al(Fe,Me)Si phase is the Fe content, an increase in Fe content will decrease resistance to exfoliation. In the artificially aged condition, the alloy is not prone to exfoliation, but shows a type of general attack. α-Al(Fe,Me)Si particles again constitute the cathodes of the corrosion cells, but the anodic phase is the M-phase (MgZn₂), which is evenly distributed.

Since the zone next to a weld bead is essentially in the solution treated condition, it will become resistant to exfoliation on post-weld artificial ageing. At some distance from the weld bead, however, there will be an ‘over-aged’ zone, where neither the hardness nor the resistance to exfoliation will be very much increased on artificial ageing. This is due to the formation of especially wide precipitate-free zones around α-Al(Fe,Me)Si and E-phase particles and around grain boundaries on ‘over-ageing’. Since the precipitate-free zones are due to vacancy depletion, these zones are supersaturated with respect to Zn and Mg and thus prone to corrosion. The attack will be confined to the matrix, especially along streaks of α-Al(Fe,Me)Si and E-phase particles.     

Microstructure and mechanical properties of Al–Si alloy modified with Al–3P

Al–Si alloy was modified with Al–3P master alloy at 740 °C. The effects of Si content (7, 8, 9, 10 and 11 wt.%) and adding amount of alterant Al–3P (0, 0.1, 0.3, 0.6, 1.0 and 1.5 wt.%) on microstructures and tensile properties of the alloy were investigated with optical microscope (OP), Image Pro Plus 6.0, scanning electron microscope (SEM) and universal testing machine. When the content of Al–3P is 0.6 wt.%, the area fraction of primary α(Al) in the Al–Si alloy increases more compared to the unmodified alloy with an increase in Si content, which could be explained by the movement of non-equilibrium eutectic point. When the Si content is constant (Al–10Si), with the increase of Al–3P content, the increased rate in area fraction of primary α(Al) phase in the Al–10Si alloy increases first and then decreases. And when 0.6 wt.% Al–3P is added, the increase in area fraction of primary α(Al) phase is the largest. Compared to the unmodified Al–10Si alloy, the tensile strength and elongation of Al–10Si alloy increase by 2.3% and 47.0%, respectively, after being modified with 0.6 wt.% Al–3P alloy. The fracture mode of the modified Al–10Si alloy is ductile fracture.     

Evolution of corrosion in cast Al alloy in antifreeze radiator coolant

Corrosion is an important issue for cast Al alloy in an engine cooling system, but how the microstructural features affect the coolant‐related corrosion behaviour is not well understood. In this research, the evolution of corrosion in an ISO 2379 cast Al alloy was studied in an antifreeze radiator coolant under heat‐rejecting conditions. Extensive analyses of microstructures and corroded surfaces were carried out using an optical microscope, scanning electron microscope equipped with energy dispersive spectroscopy and X‐ray diffractometer. Intergranular cavitation corrosion was observed to occur at interfaces between α‐Al matrix and intermetallics (Al₂Cu and Al₅FeSi) or to a less degree at interfaces between α‐Al matrix and Si phase. The large area fraction of the cathodic phases (Al₂Cu, Al₅FeSi and Si) led to the galvanic coupling between them and the adjacent anodic α‐Al matrix. The heat‐rejecting condition in antifreeze radiator coolant was favourable condition to cavitation process while severe crevice corrosion was predominant at oxygen‐depleted regions in the heat‐transfer corrosion cell.     

Effect of Be on aging behavior of an Al-Si-Cu-Mg cast alloy

The effect of Be addition on the aging behavior of UNS 03370 (Al11Si3Cu0.3Mg) was investigated by micro-hardness measurement, differential scanning calorimetry (DSC) and transmission electron microscope (TEM) analysis. Age hardening analysis shows Be additions to an Al11Si3Cu0.3Mg alloy accelerates the age hardening rate and increases the peak hardness by 15 HV during aging at 160°C. DSC shows that Be additions lead to an endothermic peak corresponding to the dissolution of Gunier Preston zones (GP I) disappear with exothermic peaks corresponding to precipitation of GP II zones and the λ′ and/or ϑ′ phases shift to low temperature. DSC and TEM analyses show that GP II zones are more effective than λ′ and/or θ′ on hardening the alloy, and Be addition increases the homogeneous nucleation density of GP II zones. The possible Be atoms participating in the precipitation process during aging and the high Be-vacancy binding energy can explain the effect of Be on aging behavior of Al11Si3Cu0.3Mg alloy.     

RuTi/1060Al脉冲熔化极氩弧熔-钎焊接头组织特征

对RuTi钛合金与1060Al进行脉冲熔化极氩弧熔-钎焊(P-GMAW),采用扫描电镜(SEM)、显微硬度仪等对RuTi/1060Al接头显微组织进行分析;对焊缝中的析出相及钛合金侧过渡区进行能谱(EDS)元素分布分析.结果表明,RuTi/1060Al接头焊缝由α-Al树枝晶及分布于树枝晶边界的α-Al+Si共晶组织组成.焊缝中出现了由Ti(Al,Si)₃金属间化合物组成的条状、块状析出相.RuTi钛合金与焊缝之间形成了一层厚度小于10 μm、主要由Ti(Al,Si)₃金属间化合物组成的锯齿状过渡区.随着焊接热输入的增加,Ti/Al过渡区由锯齿状向条状变化.钛合金热影响区主要由针状α″马氏体与条状α'马氏体组成,显微硬度为2.16~2.65 GPa.     

焊丝成分对铝/铜激光熔钎焊接头组织和性能的影响

通过添加Zn-Al焊丝成功实现了2A16铝合金/T2铜异种材料的激光熔钎焊连接,并采用扫描电子显微镜和能谱仪对接头的微观组织进行表征,同时,研究了Zn-2％Al,Zn-5％Al和Zn-10％Al?3种焊丝对接头成形、微观组织以及力学性能的影响.结果表明,铝/铜激光熔钎焊接头主要由CuZn相,Al2Cu相,Al4Cu9相...     

Effects of Solution Treatment on the Microstructure and Mechanical Properties of Al-16.9Si-4.5Cu-0.15Mg Alloy

In this paper, the microstructure and mechanical properties of Al-Si-Cu-Mg casting alloy under different solution conditions were investigated by optical metallographic and mechanical property test. The results show that the cast alloys were composed of α-Al, primary Si, eutectic Si, Al2Cu and Al7Cu2Fe phases. Three changes took place during solution treatment: Firstly, with the increase of solution temperature and the solution holding time extension, more and more Al2Cu phase was dissolved into the matrix; Secondly, with the increase of solution temperature and the solution holding time extension, morphology of eutectic Si, Al7Cu2Fe and other insoluble phases changed into more round; Thirdly, at the fixed solution temperature, if the solution time extended too long, it would cause grains, eutectic Si and other insoluble phases aggregated and coarsened. About mechanical properties, when the solution time was fixed, the hardness, tensile strength and the yield strength of the Al-Si-Cu-Mg alloy treated by T6 enhanced while the solution temperature increasing, and when the solution temperature was fixed, the ultimate tensile strength and the elongation of the Al-Si-Cu-Mg alloy treated by T6 increased at first and then decreased while the solution time increasing, but the hardness of the alloys affected less by the solution time.