Fe含量对挤压铸造Al-3.5Mg-0.8Mn合金组织性能的影响

采用拉伸和硬度测试、扫描电镜和X射线衍射仪等手段,研究了不同Fe含量对挤压铸造Al-3.5Mg-0.8Mn合金显微组织和力学性能的影响。结果表明,Fe能改善合金的力学性能,合金中只存在Al₆(FeMn)相。合金的抗拉强度和屈服强度随着Fe含量的增加而增大,伸长率随着Fe含量的增加而降低,原因是随着Fe含量增加,硬脆的Al₆(FeMn)相增多。在挤压压力为75MPa和Fe含量为0.5%时,合金的综合力学性能最佳,其抗拉强度为252MPa,屈服强度为128MPa,伸长率为28%。     

Microstructure and high temperature tensile properties of Al–Si–Cu–Mn–Fe alloys prepared by semi-solid thixoforming

The differences in the microstructure and elevated temperature tensile properties of gravity die cast, squeeze cast, and semi-solid thixoformed Al–Si–Cu–Mn–Fe alloys after thermal exposure at 300 °C were discussed. The results demonstrate that the elevated temperature tensile properties of semi-solid thixoformed alloys were significantly higher than those of gravity die cast and squeeze cast alloys, especially after thermal exposure for 100 h. The ultimate tensile strength (UTS) of semi-solid thixoformed alloys after thermal exposure at 300 °C for 0.5, 10 and 100 h were 181, 122 and 110 MPa, respectively. The UTS values of semi-solid thixoformed alloys were higher than those of heat resistant aluminum alloys used in commercial applications. The enhanced elevated temperature tensile properties of semi-solid thixoformed experimental alloys after thermal exposure can be attributed to the combined reinforcement of precipitation strengthening and grain boundary strengthening due to thermally stable intermetallic phases as well as suitable grain size.     

固溶处理和人工时效对Al-Cu合金显微组织和力学性能的影响(英文)

对Al-Cu合金进行析出强化和人工时效处理以获得优异的力学性能,如高的强度、好的韧性。其热处理工艺条件为:510～530℃固溶处理2h;60℃水淬;160～190℃人工时效2～8h。采用光学显微镜、扫描电镜、能谱分析、透射电镜和拉伸实验对经固溶和人工时效处理的Al-Cu合金的组织和力学性能进行表征。固溶处理实验结果表明,Al-Cu合金的力学性能随着固溶处理温度的升高先增加,然后降低。这是由于Al-Cu合金的残余相逐渐溶解进入基体中,从而导致析出相的数量和再结晶晶粒尺寸不断增加。相较于固溶处理温度,固溶处理时间对Al-Cu合金的影响较小。人工时效处理实验结果表明,合金经180℃时效8h,可以获得最大的拉伸强度。合金的最大拉伸强度和屈服强度随着时效时间的延长和温度的升高而升高。     

Influence of Applied Pressure on Tensile Behaviour and Microstructure of Squeeze Cast Mg Alloy AM50 with Ca Addition

The development of alternative manufacturing processes is essential for the success in applying Ca-containing magnesium alloys for automotive applications due to their relatively poor die castability. Squeeze casting with its inherent advantages has been demonstrated capable of minimizing the formation of casting defects in Mg-Al-Ca alloys. In this study, the effect of applied pressures on tensile behavior and microstructure of squeeze cast Mg-5wt.%Al-1%wt.%Ca alloy (AMX501) was investigated with the applied pressure varying from 3 to 90 MPa. The results of tensile testing indicate that the tensile properties of AMX501 alloy including ultimate tensile strength, yield strength, and elongation (E _f) increase from 153.7, 80 MPa and 3.26% to 183.7, 90.5, and 5.42% with increasing applied pressure levels from 3 to 90 MPa, respectively. The analysis of true stress versus strain curves shows that an increase in applied pressure levels result in high straining hardening rates during the plastic deformation of the alloy. Microstructural analysis and density measurements indicate that, as the applied pressure increases, the porosity levels of the alloy decrease considerably, despite of almost no significant reduction in grain sizes of the squeeze cast alloys due to their high aspect ratio of cylindrical castings. Hence, the improvement in tensile properties should be primarily attributed to casting densification resulting from applied pressures. The scanning electron microscopy observation on fractured surfaces reveals that the fracture modes of the squeeze cast alloys transit to ductile from brittle with increasing applied pressures.     

Section thickness-dependent tensile properties of squeeze cast magnesium alloy AM60

The development of alternative casting processes is essential for the high demand of light weight magnesium components to be used in the automotive industry,which often contain different section thickn...     

Mn含量对挤压铸造Al-5.0Cu-0.5Fe合金显微组织和力学性能的影响(英文)

采用拉伸性能测试、光学显微镜、扫描电镜和定量金相测试手段研究Mn含量对不同压力下挤压铸造Al-5.0Cu-0.5Fe合金显微组织和力学性能的影响。结果表明:当挤压压力为0MPa,Mn/Fe质量比达到1.6时才能将针状β-Fe相(Al7Cu2Fe)完全转变成汉字状α-Fe相(Al15(FeMn)3(CuSi)2)。而对于挤压铸造,当挤压压力为75MPa时,在Mn/Fe质量比为0.8时就可以将β-Fe相完全转变成α-Fe相。挤压铸造合金中需要的Mn含量较低,即Mn/Fe质量比较小,这主要是由于在挤压压力下富Fe相的细化以及相比例的减少。然而,加入过量的Mn将导致合金力学性能的下降,这是因为过量的Mn将导致α-Fe相的增多及这些多余的硬脆相导致的孔洞增多。     

Microstructure and tensile properties of squeeze cast magnesium alloy AM50

High-pressure die cast magnesium alloy AM50 is currently used extensively in large and complex shaped thin-wall automotive components. For further expansion of the alloy usage in automobiles, novelmanufacturing processes need to be developed. In this study, squeeze casting of AM50 alloy with a relatively thick cross section was carried out using a hydraulic press with an applied pressure of 70 MPa. Microstructure and mechanical properties of the squeeze cast AM50 with a cross-section thickness of 10 mm were characterized in comparison with the die cast counterpart. The squeeze cast AM50 alloy exhibits virtually no porosity in the microstructure as evaluated by both optical microscopy and the density measurement technique. The results of tensile testing indicate the improved tensile properties, specifically ultimate tensile strength and elongation, for the squeeze cast samples over the conventional high-pressure die cast parts. The analysis of tensile behavior show that the strain-hardening rate during the plastic deformation of the squeeze cast specimens is constantly higher than that of the die cast specimens. The scanning electron microscopy fractography evidently reveals the ductile fracture features of the squeeze cast alloy AM50.     

Microstructure and mechanical properties of Ti–Nb–Fe–Zr alloys with high strength and low elastic modulus

Zr was added to Ti–Nb–Fe alloys to develop low elastic modulus and high strength β-Ti alloys for biomedical applications. Ingots of Ti–12Nb–2Fe–(2, 4, 6, 8, 10)Zr (at.%) were prepared by arc melting and then subjected to homogenization, cold rolling, and solution treatments. The phases and microstructures of the alloys were analyzed by optical microscopy, X-ray diffraction, and transmission electron microscopy. The mechanical properties were measured by tensile tests. The results indicate that Zr and Fe cause a remarkable solid-solution strengthening effect on the alloys; thus, all the alloys show yield and ultimate tensile strengths higher than 510 MPa and 730 MPa, respectively. Zr plays a weak role in the deformation mechanism. Further, twinning occurs in all the deformed alloys and is beneficial to both strength and plasticity. Ti–12Nb–2Fe–(8, 10)Zr alloys with metastable β phases show low elastic modulus, high tensile strength, and good plasticity and are suitable candidate materials for biomedical implants.     

Cu／Mg比对AA7085显微组织与性能影响

采用熔铸法制备具有不同Cu／MgLk（0．67,1．0,1．06,1．6）的AA7085铝合金。采用金相显微镜、扫描电镜、力学性能测试和腐蚀测试研究Cu／Mg比对基体合金显微组织、力学性能和腐蚀行为的影响。结果表明,当Cu／Mg比为1．6时,AA7085铝合金具有更好的抑制再结晶能力和抗腐蚀性能。当Cu／Mg比为0．67时,铝合金具有更为优越的力学性能,其抗拉强度与屈服强度分别达到586和550MPa。而当Cu／Mg比为1．0时,合金的力学性能和耐腐蚀性能均下降。     

Effect of Cu addition on microstructure and properties of Mg-10Zn-5Al-0.1Sb high zinc magnesium alloy

To improve the strength,hardness and heat resistance of Mg-Zn based alloys,the effects of Cu addition on the as-cast microstructure and mechanical properties of Mg-10Zn-5Al-0.1Sb high zinc magnesium alloy were investigated by means of Brinell hardness measurement,scanning electron microscopy (SEM),energy dispersive spectroscopy (EDS),XRD and tensile tests at room and elevated temperatures.The results show that the microstructure of as-cast Mg-10Zn-5Al-0.1Sb alloy is composed of α-Mg,t-Mg32(Al,Zn)49,φ-Al2Mg5Zn2 and Mg3Sb2 phases.The morphologies of these phases in the Cu-containing alloys change from semi-continuous long strip to black herringbone as well as particle-like shapes with increasing Cu content.When the addition of Cu is over 1.0wt.%,the formation of a new thermally-stable Mg2Cu phase can be observed.The Brinell hardness,room temperature and elevated temperature strengths firstly increase and then decrease as the Cu content increases.Among the Cu-containing alloys,the alloy with the addition of 2.0wt.% Cu exhibits the optimum mechanical properties.Its hardness and strengths at room and elevated temperatures are 79.35 HB,190MPa and 160MPa,which are increased by 9.65%,21.1% and 14.3%,respectively compared with those of the Cu-free one.After T6 heat treatment,the strengths at room and elevated temperatures are improved by 20% and 10%,respectively compared with those of the as-cast alloy.This research results provide a new way for strengthening of magnesium alloys at room and elevated temperatures,and a method of producing thermally-stable Mg-10Zn-5Al based high zinc magnesium alloys.     

Effects of Cu content on microstructure and mechanical properties of rheo-diecasting Al-6Zn-2Mg-xCu alloys

A systematic study on how Cu content affects the microstructure and mechanical properties of rheo-diecasting Al-6Zn-2Mg-xCu alloys during solution treatment and ageing heat treatment was conducted. The swirled enthalpy equilibrium device (SEED) was adopted to prepare the semi-solid slurry of Al-6Zn-2Mg-xCu alloys. The microstructure development and mechanical properties were studied using optical microscopy (OM), scanning electron microscopy (SEM), X-ray diffraction (XRD), differential scanning calorimetry (DSC), as well as hardness and tensile testing. The grain boundary and shape factor were calculated using image processing software (Image-Pro Plus 6.0). Results show that the alloys are composed of typical globular primary α-Al grains, eutectic phases, and smaller secondary α-Al grains. After solution and ageing heat treatment, the eutectic phases are dissolved into Al matrix when the Cu content is lower than 1.5wt.%, while some eutectic phases transform into Al₂CuMg (S) phases and remain at grain boundaries when Cu content reaches 2wt.%. T6 heat treatment significantly enhances the mechanical properties of rheo-diecasting Al-6Zn-2Mg-xCu alloys. When Cu concentration is 0.5wt.%–1.5wt.%, the ultimate tensile strength, yield strength and elongation of T6 treated alloys rise to around 500 MPa, 420 MPa, and 18%, respectively.

     

高强度铸造铝铜合金微观组织对性能的影响

研究了微观组织对ZL205A系铸造铝铜合金热处理后强度和塑性的影响。结果表明:影响该合金强度和塑性性能的微观组织主要是晶粒尺寸、晶内、晶界沉淀相,弥散析出相和未固溶相。晶界处主要是θ相、N相、初生T相的混合组织,当呈针状或条状时恶化合金性能,当呈半连续的骨骼对合金性能影响较小。晶内细小弥散的二次T相是主要强化相,当T相聚集长大会降低强度。过剩相θ相,当呈大块分布时降低合金塑性,当呈细小均匀分布时对合金性能影响较小。     

微量Nd的添加对Mg-Al-Zn合金微观组织和高温力学性能的影响

分析研究了微量Nd的添加对Mg-Al-Zn合金显微组织和高温力学性能的影响.结果表明:Nd的加入,显著细化了合金的铸态组织,同时出现了新相Al3Nd化合物.当Nd添加量为1.0%时,可使铸态Mg-8.5Al-0.5Zn合金在150℃高温下的抗拉强度达到最大值为160MPa,和未加入Nd的合金相比提高了13.2%.     

铁元素添加对Cu基非晶合金结构及力学性能的影响

利用铜模吸铸法制备了(Cu_(0.46)Zr_(0.44)Al_(0.08)Dy_(0.02))_(100-x)Fe_x(x=0,1,3,5,7)非晶合金,利用X射线衍射仪(XRD)、同步热分析仪(DSC)、透射电镜(TEM)、万能试验机和扫描电镜(SEM)研究了Fe元素添加对Cu基非晶合金结构及力学性能的影响。结果表明:Fe元素的适量添加有利于改善Cu_(46)Zr_(44)Al_8Dy_2块体非晶合金的结构,当添加原子分数为1%和3%Fe时,合金为完全非晶结构,并且出现富Fe相和富Cu相两相分离。Fe元素的适量添加有利于提高Cu_(46)Zr_(44)Al_8Dy_2合金的强度和塑性,当添加3%Fe时,块体非晶合金的抗压强度σ_f和塑性ε_p分别达到1835 MPa和0.5%。     

Effects of Yb addition on microstructures and mechanical properties of 2519A aluminum alloy plate

The effects of Yb content on the microstructures and mechanical properties of 2519A aluminum alloy plate were investigated by means of tensile test,optical microscopy,transmission electron microscopy,scanning electron microscopy and X-ray diffractometer.The results show that addition of 0.17% (mass fraction) Yb increases the density of θ' particles of the 2519A alloy plate and reduces the coarsening speed rate of θ' phase at 300 ℃.Therefore,tensile strength is enhanced from 483.2 MPa to 501.0 MPa at room temperature and is improved from 139.5 MPa to 169.4 MPa at 300 ℃.The results also show that with the addition of 0.30% (mass fraction) Yb,the mechanical properties increase at 300 ℃ and decrease at room temperature.With Yb additions,the Al7.4Cu9.6Yb2 phase is found whilst the segregated phases of as-cast alloys along grain boundaries become discontinuous,thin and spheroidized.     

激光熔化沉积CrMnFeCoNi高熵合金组织和低温力学性能

采用激光熔化沉积和铸造技术分别制备了CrMnFeCoNi高熵合金。通过X射线衍射(XRD)、金相腐蚀、扫描电镜(SEM)和力学拉伸实验等分析手段对不同方法制备的CrMnFeCoNi高熵合金相组成、微观组织及力学性能进行了对比研究。结果表明:通过激光熔化沉积和铸造技术制备的CrMnFeCoNi高熵合金均为面心立方(FCC)单相固溶体结构;采用激光熔化沉积技术制备的CrMnFeCoNi高熵合金具有更为均匀的元素分布;随着温度从293 K降低到77 K,激光熔化沉积技术制备的CrMnFeCoNi高熵合金的拉伸强度与塑性分别从518 MPa、55%提升到878 MPa、95%,表现出优异的低温力学性能。     

Cu含量对重力铸造Al-Cu-Mg-Sc合金组织及力学性能的影响

在重力铸造条件下制备了不同Cu含量(4%~6%,质量分数,下同)Al-Cu-Mg-Sc合金,采用500 ℃×4 h＋520 ℃×6 h的双级固溶,水冷后进行175 ℃×5 h时效。通过维氏硬度测试、室温拉伸性能测试试验、扫描电镜分析(SEM)等手段,研究了不同Cu含量对试验合金显微组织和力学性能的影响,进而优化Al-Cu-Mg-Sc铝合金成分。结果表明,经热处理后,随Cu含量从4.26%提高至5.58%,Al₂Cu析出相含量持续提高,热处理后合金屈服强度从191 MPa提升至216 MPa,抗拉强度从323 MPa提升至355 MPa,伸长率维持在13%附近。然而,当Cu含量较高时(6.13%),微观组织中Al₂Cu相体积分数较高,固溶后进入基体的Al₂Cu相数目有限,有大量Al₂Cu相残留在晶界处,经过时效处理后,合金的强化效果不能随Cu含量的增加而继续提升。因此整体上,随Cu含量提高,时效态高Cu含量合金的硬度和抗拉强度先增加随后趋于平稳,断后伸长率呈现先增加后降低的规律。Cu含量为5.58%的铸造Al-Cu-Mg-Sc铝合金时效后获得最佳综合性能,其硬度为117 HV,抗拉强度和屈服强度分别为355 MPa、216 MPa,断后伸长率为13.5%。     

Effect of solidification parameters on mechanical properties of directionally solidified Al-Rich Al-Cu alloys

Al_(100?x)-Cu_x alloys (x=3 wt%, 6 wt%, 15 wt%, 24 wt% and 33 wt%) were prepared using metals of 99.99% high purity in vacuum atmosphere. These alloys were directionally solidified under steady-state conditions by using a Bridgman-type directional solidification furnace. Solidification parameters (G, V and ), microstructure parameters (λ₁, λ₂ and λ_E) and mechanical properties (HV, σ) of the Al-Cu alloys were measured. Microstructure parameters were expressed as functions of solidification parameters by using a linear regression analysis. The dependency of HV, σ on the cooling rate, microstructure parameters and composition were determined. According to experimental results, the microhardness and ultimate tensile strength of the solidified samples was increased by increasing the cooling rate and Cu content, but decreased with increasing microstructure parameters. The microscopic fracture surfaces of the different samples were observed using scanning electron microscopy. Fractographic analysis of the tensile fracture surfaces showed that the type of fracture significantly changed from ductile to brittle depending on the composition.     

Effects of Fe content on microstructure and properties of Cu–Fe alloy

Cu–Fe alloys with different Fe contents were prepared by vacuum hot pressing. After hot rolling and aging treatment, the effects of Fe content on microstructure, mechanical properties and electrical conductivity of Cu–Fe alloys were studied. The results show that, when w(Fe)<60%, the dynamic recrystallization extent of both Cu phase and Fe phase increases. When w(Fe)≥60%, Cu phase is uniformly distributed into the Fe phase and the deformation of alloy is more uniform. With the increase of the Fe content, the tensile strength of Cu–5wt.%Fe alloy increases from 305 MPa to 736 MPa of Cu–70wt.%Fe alloy, the elongation decreases from 23% to 17% and the electrical conductivity decreases from 31%IACS to 19%IACS. These results provide a guidance for the composition and processing design of Cu–Fe alloys.     

不同压力下挤压铸造铝铜合金的组织与性能

采用挤压铸造工艺制备出一种新开发的、高强韧铝铜合金.T5热处理状态下其抗拉强度达到433 MPa,伸长率为14%.通过对该合金力学性能及其显微组织的研究表明,铸态和经T5热处理的抗拉强度和伸长率均随压力的增加而增大,在压力为50MPa时达到最大值,但在铸态下,未加压力的铸造合金其硬度高于挤压铸造的合金硬度.随挤压力增加,晶粒明显细化,二次枝晶增加,枝晶间距减小.