Ni元素对Al-Cu-Mn合金组织及力学性能的影响

为研究添加Ni元素对Al-5.0Cu-0.6Mn合金组织及力学性能的影响,通过硬度试验、拉伸力学试验及摩擦磨损试验对合金力学性能进行研究;采用扫描电子显微镜、激光共聚焦显微镜及透射电子显微镜对合金微观组织进行检测分析。结果表明：向Al-5.0Cu-0.6Mn合金中添加Ni元素后,由于Al₃CuNi相析出的强化作用,并且与基体结合良好的增强相颗粒能均匀分布于合金中,使得合金硬度和强度大幅提高,摩擦磨损深度显著降低,综合力学性能得到有效的提升。当Ni元素的添加量为0.3%(质量分数)时,由于T相(Al₂₀Cu₂Mn₃)和Al₃CuNi相分布比较均匀,合金综合性能较为理想,其HV硬度、抗拉强度、摩擦磨损系数分别为126.4 MPa、395.2 MPa、0.12。     

压力对A380铝合金的铸造组织和力学性能的影响

对A380铝合金进行了挤压铸造成型和传统重力铸造成型,并制得试样.采用偏光显微镜、扫描电镜、定量金相分析、拉伸性能测试等手段,研究在不同压力下挤压铸造A380铝合金的铸造组织和力学性能.结果表明:当压力在0~75 MPa范围内时,随着压力的增加,一次枝晶臂尺寸和气孔率得到大幅下降,共晶组织体积分数增加;二次枝晶臂间距减小;针状富铁β-Al₅ FeSi相尺寸大幅度减小,同时有部分汉字状α-Al₈(Fe,Mn)₃Si₂相生成.当压力在75~100 MPa范围内时,压力继续增加对合金组织细化、第二相形貌改善和力学性能提高的作用不明显.挤压铸造试件与重力铸造试件相比,气孔率减小,显微组织细化,力学性能显著提高.当压力为75 MPa时,挤压铸造A380铝合金的铸态抗拉强度和伸长率分别比重力铸造提高19%和65%.      

砂型铸造用过共晶Al-Si合金的应用

<正>欧洲专利US9109271本专利涉及一种砂型铸造用含镍的过共晶Al-Si合金,它的主要化学成分如下(质量分数,%):18~20Si、0.3~1.2Mg、3.0~6.0Ni、≤0.6Fe、≤0.4Cu、≤0.6Mn、≤0.1Zn,余量为Al。该合金中镍的含量范围很窄,还可含有≤2.0Co,也可以不含Fe、Cu和Mn。本专利所述含镍的过共晶铝硅合金最好采用砂型铸造,它更适用于在1.10MPa压力下的消失模铸造方法,用来生产高热性能     

Fe对Ni-Mn-Ga形状记忆合金相变和力学性能的影响

研究了Fe含量对Ni₅₆Mn_25-xFe_xGa₁₉(x=0~10)合金的微观组织结构、相变行为、力学性能和记忆特性的影响规律.当x ≤ 4时,Ni₅₆Mn_25-xFe_xGa₁₉合金仍然保持着单一的四方结构马氏体相;当x ≥ 6时,合金呈现为马氏体相和面心立方γ相组成的双相结构.相对于马氏体相,γ相为富Ni和富Fe相,其含量随Fe含量的增加而增加.随着Fe含量增加,合金的马氏体相变温度逐渐降低,其峰值温度从x=0时的356℃降低至x=10时的170℃,这主要归因于马氏体相尺寸因素和电子浓度的综合作用.通过添加Fe替代Mn在合金中引入的γ相可提高合金的强度和塑性,但最大形状记忆回复应变从x=0时的5.0%降低到x=6时的2.0%.      

超声对熔盐电解法制备Al-7Si-Sc合金组织的影响

Al-Si系合金在现代工业、交通等领域广泛应用,合金元素钪可进一步改善其加工和使用性能.采用超声协同熔盐电解法制备Al-7S-Sc三元合金,研究探索超声作用对合金组织及强化相分布的影响.发现超声协同熔盐电解制得合金中Sc含量提高,团簇共晶硅组织和AlSi₂Sc₂相显著细化,共晶硅团簇尺寸由约500降低至200 μm,减小约60%,细化后AlSi₂Sc₂相分布均匀.超声协同电解法可显著优化Al-7Si-Sc合金组织,有助于控制改善现行工艺中合金元素偏聚、组织不均匀现象.      

超音速气雾化过共晶Al-Si合金粉末特性及组织

利用超音速气雾化法制备过共晶Al-Si快凝合金粉末。对合金粉末形貌特征、组织结构及相组成进行研究,表明合金粉末细小均匀,组织主要颗粒状Si相和针状金属间化合物Al9FeSi3组成,而且尺寸比较细小,分布也较均匀。     

变质处理及成分对大过共晶铝硅合金耐磨性的影响

对变质处理和未变质的过共晶Al-Si合金的耐磨性进行了研究。结果表明:Al-Si合金的磨损率随着硅含量的增加先下降后升高,相同成分Al-Si合金经过变质处理后的耐磨性比未变质处理过的耐磨性提高16%～30%,这说明除了Si含量影响着Al-Si合金的耐磨性以外,Si相的形态和分布对Al-Si合金的耐磨性也有很大的影响。对磨损机理的分析表明,磨损主要为磨粒磨损,磨粒来源是大块初生Si的破碎剥落。     

含镍的过共晶铝硅合金的砂型铸造方法

正欧洲专利WO2014158384本专利提供一种含3.0%~6.0%Ni的过共晶铝硅合金,但不含Fe、Cu、Mn等元素,可用于砂型铸造,特别是消失模铸造,其耐热性能和机械加工性能都很好,打破了过共晶铝硅合金在很大范围内不能用于砂型铸造的限制。     

Nb含量对Al0.3CoCrFeNi高熵合金组织与性能的影响

采用真空电弧炉制备了Al_0.3CoCrFeNiNb_x(x为摩尔比,x=0, 0.1, 0.3, 0.5, 0.7, 1.0)高熵合金棒材,用X射线衍射(XRD)、光学显微镜(OM)、扫描电镜(SEM)、能谱仪(EDS)、显微维氏硬度计和万能试验机对合金的微观组织和性能进行了研究。结果表明,Al_0.3CoCrFeNi合金的微观组织为单相面心立方(fcc);添加Nb后,合金由fcc相和Laves相组成,并随着Nb含量的增加,Laves相体积分数逐渐增多;至Al_0.3CoCrFeNiNb_1.0时,基体相从fcc相变为Laves相。Al_0.3CoCrFeNiNb_x合金组织随Nb含量变化经历了亚共晶到过共晶的转变,同时衍射峰(111)fcc先向小角度移动后向大角度移动,晶格常数先增大后减小。Nb元素的增加可以有效提高Al_0.3CoCrFeNiNb_x合金的强度和硬度,硬度呈近似线性增加,从Al_...     

钴基高温合金GH5605铸态组织及高温扩散退火过程中元素再分配

利用光学显微镜(OM)、场发射扫描电子显微镜(FESEM)、能谱分析(EDS) 并结合热力学及动力学计算结果对采用真空感应熔炼和电渣重熔二联工艺生产的GH5605合金电渣锭的枝晶形貌、元素偏析和析出相进行分析.探索了合金的高温扩散退火制度并结合差示扫描量热仪(DSC) 和热压缩模拟实验分析高温扩散退火前后的合金特征.结果表明: GH5605合金中的枝晶和元素偏析情况较轻, 主要偏析元素是Cr和W并在枝晶间处偏聚, 电渣锭中的主要析出相包括奥氏体、晶界M₂₃C₆以及晶内和晶界处的奥氏体与M₂₃C₆板条状共晶相.经1210℃/8 h扩散退火处理后枝晶和元素偏析基本消除, 共晶相基本回溶.      

合金化Cr优化含Fe过共晶Al-Si合金显微组织及其机制

采用传统铸造工艺和喷射成形技术制备了无Cr和含Cr的含Fe过共晶Al-Si合金,并利用SEM(EDS)、XRD及DSC对其显微组织、相组成及相变过程进行了研究。结果表明:2%Cr的加入不光使铸态粗大针片状的δ-Al4FeSi2相变为"骨骼状"α-Al(Fe,Cr)Si相,而且使沉积态Al-25Si-5Fe-3Cu合金中短棒状的富铁相(～10μm左右)被尺寸小于3～5μm的颗粒状α-Al(Fe,Cr)Si相所替代,从而细化的组织更有利于合金性能的提高。等温处理实验结果显示沉积态含Cr合金具有较好的组织热稳定性,其主要归因于颗粒状α-Al(Fe,Cr)Si相自身的高温稳定性,而沉积态Al-25Si-5Fe-3Cu合金热稳定差主要由于β-Al5FeSi相的长大和A7Cu2Fe相的形成。另外,结合显微组织和喷射成形工艺特点对沉积态组织形成机制分析发现α-Al(Fe,Cr)Si相有可能通过直接从液相析出和经δ-Al(Fe,Cr)Si相转变而来。     

Effect of iron (Wt.%) on adhesive wear response of Al-12Si-1Cu-0.1Mg alloy in dry sliding conditions

The presence of iron leads to different types of intermetallics in Al-Si alloys, among them needle shaped β-phase (Al₅FeSi) can lead to variations in hardness of the Al-Si alloy which ultimately can affect the wear resistance of the alloy. In this paper, the effect of iron on wear behavior of cast Al-Si alloys has been reported. Sliding wear behavior of eutectic alloy Al-12Si-1Cu-0.1Mg was investigated in dry sliding conditions by using pin-on-disk test configuration against heat treated EN31 steel counter-surface at room temperature. Sliding wear behavior has been evaluated at four normal loads of 5, 20, 50 and 70 N and two sliding speeds, 2 m/s and 4 m/s. Worn pin surfaces were examined by scanning electron microscopy (SEM) for analyzing wear mechanisms. The wear mechanism has been found to be mild oxidative type at lower sliding speed of 2m/s for entire range of loads used in the study. Transition to severe metallic wear occurs at higher sliding speed of 4 m/s at normal load of 5 N. Hardness of the alloy increased with increase in iron addition primarily due to presence of needle shaped Fe-rich intermetallics but it leads to an increased wear rate.     

载荷对Fe-Cr-C-Nb堆焊合金松散磨粒磨损行为的影响

采用熔化极气体保护焊技术（gas metal arc welding,GMAW）制备了Fe-Cr-C-Nb堆焊合金,对合金在不同法向载荷（70~190 N）下进行干砂/橡胶轮松散三体磨粒磨损实验。通过X射线衍射分析、扫描电子显微镜观察、能谱分析、磨损失重测试、体视显微镜观察、激光扫描共焦显微镜观察和维氏硬度测量等手段表征了合金显微组织与磨痕特征,研究了合金在不同法向载荷作用下磨损行为的变化。结果表明:堆焊合金显微组织主要由初生奥氏体基体、网状共晶组织及分布于基体上的NbC硬质相组成;合金磨损损失、磨痕深度随法向载荷增大而增大,磨损机制主要为奥氏体基体的微切削及NbC、M₇C₃的脆性剥落;法向载荷的提高加剧了磨痕亚表面的加工硬化,从而提高了奥氏体基体耐磨性,这导致磨损损失及磨痕深度增长幅度缓慢。     

Cr3C2/Ni3Al复合材料耐磨性提高的机制分析

为了探讨Cr₃C₂强化相提高Cr₃C₂/Ni₃Al复合材料耐磨性的机制, 本文采用热等静压技术制备了Ni₃Al合金和Cr₃C₂/Ni₃Al复合材料, 借助纳米压痕仪对Ni₃Al合金和Cr₃C₂/Ni₃Al复合材料中各组成相的力学性能进行了表征, 利用销-盘式摩擦磨损试验机研究了热等静压Ni₃Al合金和Cr₃C₂/Ni₃Al复合材料的耐磨性能, 并结合扫描电子显微镜和纳米压痕仪分析了材料磨损表面形貌和磨损次表面层硬度变化.结果表明, Cr₃C₂的添加提高了复合材料基体的硬度, Cr₃C₂/Ni₃Al复合材料中各组成相的纳米硬度和弹性模量由基体相、扩散相到硬芯相是逐渐增大的, 呈现出梯度变化, 有利于提高Cr₃C₂/Ni₃Al复合材料的耐磨性.在本研究实验条件下, Ni₃Al合金和Cr₃C₂/Ni₃Al复合材料表面的磨损形式主要为磨粒磨损, Cr₃C₂/Ni₃Al复合材料表现出更加优异的耐磨性能.Cr₃C₂/Ni₃Al复合材料耐磨性能的提高主要跟碳化物强化相阻断磨粒切削、减弱摩擦副间相互作用、减小加工硬化层厚度、磨粒尺寸等因素有关.      

Iron-rich intermetallic phases and their role in casting defect formation in hypoeutectic Al−Si alloys

Iron is the most common and detrimental impurity in aluminum casting alloys and has long been associated with an increase in casting defects. While the negative effects of iron are clear, the mechanism involved is not fully understood. It is generally believed to be associated with the formation of Fe-rich intermetallic phases. Many factors, including alloy composition, melt superheating, Sr modification, cooling rate, and oxide bifilms, could play a role. In the present investigation, the interactions between iron and each individual element commonly present in aluminum casting alloys, were investigated using a combination of thermal analysis and interrupted quenching tests. The Fe-rich intermetallic phases were characterized using optical microscope, scanning electron microscope, and electron probe microanalysis (EPMA), and the results were compared with the predictions by Thermocalc. It was found that increasing the iron content changes the precipitation sequence of the β phase, leading to the precipitation of coarse binary β platelets at a higher temperature. In contrast, manganese, silicon, and strontium appear to suppress the coarse binary β platelets, and Mn further promotes the formation of a more compact and less harmful α phase. They are therefore expected to reduce the negative effects of the β phase. While reported in the literature, no effect of P on the amount of β platelets was observed. Finally, attempts are made to correlate the Fe-rich intermetallic phases to the formation of casting defects. The role of the β phase as a nucleation site for eutectic Si and the role of the oxide bifilms and AlP as a heterogeneous substrate of Fe intermetallics are also discussed.     

Effects of Melt Thermal-Rate Treatment on Fe-Containing Phases in Hypereutectic Al-Si Alloy

In this paper, effects of melt thermal-rate treatment (MTRT) on Fe-containing phases in hypereutectic Al-Si alloy were investigated. Results show that MTRT can refine microstructures and improve castability, mechanical properties, wear characteristics, and corrosion resistance of Fe-containing Al-Si alloy. When Al-15Si-2.7Fe alloy is treated with MTRT by 1203 K (930 °C) melt: coarse primary Si and plate-like Fe-containing phase both can be refined to small blocky morphology, and the long needle-like Fe-containing phase disappears almost entirely; ultimate tensile strength and elongation are 195 MPa and 1.8 pct, and increase by 12.7 and 50 pct, respectively; and the wear loss and coefficient of friction decrease 7 to 17 and 24 to 30 pct, respectively, compared with that obtained with conventional casting technique. Corrosion resistance of the alloy treated with MTRT by 1203 K (930 °C) melt is the best, that is it has the lowest i _corr value and the highest E _corr value. Besides, effects of MTRT on Al-15Si-xFe (x = 0.2, 0.7, 1.7, 3.7, 4.7) alloys were also studied, MTRT can only refine microstructure and improve mechanical properties of Al-15Si alloy with 0.7 to 3.7 pct Fe content greatly in the present work.     

Effect of erbium on properties and microstructure of Al-Si eutectic alloy

Eutectic Al-12.6 wt.%Si alloys with various contents of the rare earth dement Er were prepared by the conventional casting technique.The effect of Er on the microstructure and properties of the eutectic Al-Si alloys was investigated using optical microscopy,scanning electron microscopy as well as the friction and wear tests.It was found that the addition of Er obviously improved the anti-wear properties,and reduced the friction coefficient of the alloys.The appropriate addition of Er would change the size and shape of the eutectic silicon,and thereby refine the microstructure of the Al-Si alloys.The refinement mechanism was also discussed.     

铝硅系铸造铝合金的原位统计分布分析

The element distribution analysis for the Al-Si casting aluminum alloys has been done by metal original position analyzer(OPA). The quantitative distribution analysis results of Si, Fe, Cu, Mn and Ti have been obtained by selecting suitable spectrum reference materials and optimizing the instrumental parameters. The content results of five elements by OPA method have good coincidence with the values determined byspark source atomic emission spectrometer. The scanning analysis results show that the distribution of Si, Cu and Ti is homogeneous and some obvious segregation of Fe and Mn has been found in two real aluminum alloys and the content distributions of two elements are very similar. It can be concluded thatthere are some compound of Fe and Mn in casting aluminum alloys by the result of multi-element spectrum channel combination analysis. The conclusion also has good agreement with the results by scanning electron microscope and energy spectrum analysis.     

Extrusion, Properties, and Failure of Spray-Formed Hypereutectic Al-Si Alloys Based on the Optimization of Fe-Bearing Phase

Based on the densification of the spray-formed hypereutectic Al-Si (hyper-AS) alloys, the microstructural evolution, mechanical properties, as well as the failure are studied in this investigation. The appropriate process and parameters for the densification of the deposits are gained from the thermomechanical simulation. Besides of the spray-formed Al-25Si-5Fe-3Cu (3C) alloy, the microstructures of other spray-formed alloys with Mn/Cr addition are stable without coarsening of the refined α-Al(Fe,TM)Si (TM = Mn/Cr/(Mn+Cr)) particles, which can improve the heat resistance. Especially, a great number of the submicrosized α-Al(Fe,TM)Si phases are observed in the hot-extruded TM-containing alloys. The critical ranges of the major parameter TM/Fe mass ratios that can affect the formation of the α-Al(Fe,TM)Si phases in the cast or spray-formed hyper-AS alloys are severally determined. The structure and lattice constant of the refined α-Al(Fe,TM)Si phases also are characterized. The mechanical properties of the current extruded hyper-AS alloys at room or elevated temperatures are close to or higher than some commercial alloys or other published results. Therefore, the hyper-AS alloys can be proposed as new lightweight, heat-resistant, and high-strength alloys, which can be used in the complex working conditions, such as advanced engine systems. The main reason for the enhanced properties would be the formation of a large quantity of microsized/submicrosized α-Al(Fe,TM)Si phases and abundant dislocations, which can greatly reinforce the matrix and transform the brittle fracture of the needle-like Fe-bearing phases into ductile fracture.