Al-Zn-Mg-Cu-Zr-Sc合金铸态Al3(Sc，Zr)相形貌的研究

采用金相显微镜、扫描电镜和能谱分析,研究Sc细化Al-Zn-Mg-Cu-Zr合金铸态组织的机制和一次Al3(Sc,Zr)粒子的形貌特征。结果表明:从熔体中析出的Al3(Sc,Zr)一次粒子是α(Al)固溶体的有效形核剂,该粒子以亚稳的L12型Al3Zr为核心,形成富钪与富锆Al3(Sc,Zr)层相间排列的多层复合结构。在Al-9.0Zn-2.5Mg-2.5Cu-0.15Zr合金中添加0.20%～0.60%(质量分数)的钪,合金的铸态组织由粗大的树枝晶变为等轴晶,随着钪含量的增加,合金铸态组织得到进一步细化。     

Al-9.0Zn-2.5Mg-2.5Cu-0.15Zr-0.2Sc合金中Al3(Sc,Zr)粒子的析出行为

采用金相显微镜、扫描电镜、透射电镜和能谱分析,研究了Al-9.0Zn-2.5Mg-2.5Cu-0.15Zr-0.2Sc合金中Al3(Sc,Zr)粒子的形貌及其细化合金铸态组织、提高合金性能的机理.从熔体中析出的一次Al3(Sc,Zr)粒子是α(Al)固溶体的有效形核剂,该粒子以亚稳的Ll2型Al3Zr为核心,形成富钪与富锆Al3(Sc,Zr)层相间排列的多层复合结构;铸态合金退火后,α(Al)基体内析出二次Al3(Sc,Zr)粒子,经450℃×3 2h退火,二次Al3(Sc,Zr)粒子尺寸为16 ～ 23 nm,与α(Al)基体完全共格,该粒子钉扎位错和亚晶界,阻碍合金再结晶过程,提高合金再结晶温度;合金经RRA处理后,抗拉强度、伸长率和电导率分别为:667.5 MPa、7.5％和37.8％ IACS,具有良好的综合性能.     

添加Sc和提高Zn含量对7085铝合金力学性能、淬火敏感性和耐蚀性能的影响

在7085铝合金基础上添加Sc和提高Zn含量制备了3种不同成分的热轧薄板样品,在470℃加热1 h后分别风冷(FC)和水冷(WC)淬火,然后进行120℃×24 h人工时效。再采用室温拉伸和晶间腐蚀试验及光学显微镜和透射电镜观察等试验方法,研究Sc和Zn对7085铝合金力学性能和耐蚀性能的影响。结果表明,添加Sc可以显著细化晶粒、钉扎位错、抑制再结晶、提高形核率、降低晶界无沉淀析出带的宽度及晶界析出相尺寸,从而有利于提高合金的强度与耐蚀性能,淬火敏感性也有所提高。在含Sc的基础上进一步提高Zn含量会使淬火诱导相的析出驱动力增大,晶内析出相和晶界析出相的数量增加,时效后合金的强度进一步提高,淬火敏感性显著增强,耐蚀性能有所下降。     

含钪Al-9.0Zn-2.5Mg-1.2Cu-0.15Zr合金铸态组织与力学性能

采用铸锭冶金法制备了Al-9.0Zn-2.5Mg-1.2Cu-0.15Zr、Al-9.0Zn-2.5Mg-1.2Cu-0.12Sc-0.15Zr和Al-9.0Zn-2.5Mg-1.2Cu-0.20Sc-0.15Zr三种合金,采用金相显微镜、扫描电子显微镜和透射电子显微镜,研究了三种合金铸态及不同热处理状态下的显微组织,测试了不同热处理状态下合金的力学性能。结果表明,Sc含量增加可以提高Al-Zn-Mg-Cu-Zr合金的抗拉强度和伸长率,Al-9.0Zn-2.5Mg-1.2Cu-0.15Zr-0.20Sc经固溶和T6处理后,抗拉强度达到774.6 MPa,伸长率为8.3%。其作用机理主要为Sc含量增加,使合金中Al(3 Sc,Zr)引起的细晶强化、亚结构强化和弥散强化更进一步加强。     

Sc、Zr对Al-Zn-Mg-Cu合金组织与性能的影响

制备了成分Al-5．8Zn-2．5Mg-1．6Cu-0．2Cr和Al-5．8Zn．2．5Mg-1．6Cu-0．2Cr-0．23Sc-0．12Zr的两种合金。通过金相显微镜及电镜观察、力学性能及腐蚀性能测试,分析了两种合金不同处理状态的显微组织及其不同状态下的力学性能和腐蚀性能。结果表明,添加Sc、Zr能显著细化合金的铸态组织,对合金的力学性能及腐蚀性能也起到极大的提高作用。添加Sc、Zr的2#合金与1#合金相比较,经T6处理后,前者的抗拉强度提高110N／mm^2,屈服强度提高91N／mm^2,伸长率也略有提高。     

Effect of minor Sc and Zr on superplasticity of Al-Mg-Mn alloys

The effect of Sc and Zr on the superplastic properties of Al-Mg-Mn alloy sheets was investigated by control experiment. The superplastic properties and the mechanism of superplastic deformation of the two alloys were studied by means of optical microscope, scanning electronic microscope and transmission electron microscope. The elongation to failure of Al-Mg-Mn-Sc-Zr alloy is larger than that of Al-Mg-Mn alloy at the same temperature and initial strain rate. The variation of strain rate sensitivity index is similar to that of elongation to failure. In addition, Al-Mg-Mn-Sc-Zr alloy exhibits higher strain rate superplastic property. The activation energies of the two alloys that are calculated by constitutive equation and linear regression method approach the energy of grain boundary diffusion. The addition of Sc and Zr decreases activation energy and improves the superplastic property of Al-Mg-Mn alloy. The addition of Sc and Zr refines the grain structure greatly. The main mechanism of superplastic deformation of the two alloys is grain boundary sliding accommodated by grain boundary diffusion. The fine grain structure and high density of grain boundary, benefit grain boundary sliding, and dynamic recrystallization brings new fine grain and high angle grain boundary which benefit grain boundary sliding too. Grain boundary diffusion, dislocation motion and dynamic recrystallization harmonize the grain boundary sliding during deformation.     

Sc元素对激光选区熔化TiB2/AlSi10Mg复合材料组织和性能的影响

采用稀土元素Sc对激光选区熔化TiB₂/AlSi10Mg复合材料进行变质处理,借助场发射扫描电镜、电子探针显微分析仪、显微硬度计以及电子万能试验机等,分别研究了添加Sc元素和固溶时效热处理对复合材料显微组织、密度和力学性能的影响。结果表明:与TiB₂/AlSi10Mg复合材料相比,Sc元素的加入可以进一步细化Al-Si共晶,产生细晶强化和弥散强化作用,TiB₂/AlSi10MgSc复合材料的抗拉强度和显微硬度分别提升了56.7 MPa (14.4%) 和15.3 HV0.1 (11.3%)。激光选区熔化TiB₂/AlSi10MgSc复合材料的硬度和强度随着固溶温度升高而逐渐降低,但伸长率得到明显改善。     

Effects of Sc, Zr and Ti on the microstructure and properties of Al alloys with high Mg content

The effects of trace Sc, Zr, and Ti on the microstructure and hardness of Al alloys with high Mg content (Al-6Mg, Al-8Mg, and Al-10Mg) were studied by optical microscope, scanning electron microscopy (SEM), transmission electron microscopy (TEM), and Brinell hardness. The grain size of the as-cast alloys was refined by the addition of Sc and Zr, and it was further refined by the addition of Ti. With the same contents of Sc, Zr, and Ti, an increase in Mg content was beneficial to the refinement due to the solution of Mg into α-Al. The refined micro-structures of the as-cast alloys were favorable for Brineil hardness. Addition of Sc, Zr, and Ti to the Al-10Mg alloy results in the improve-ment of peak hardness and it is about 45% higher than that of the Al-10Mg alloy, which is due to fine precipitations of Al_3(Sc_(1-x)Zr_x), Al_3(Sc_(1-x)Ti_x), and Al_3(Sc_(1-x-y)Zr_xTi_y).     

Effect of Sc and Zr on microstructures and mechanical properties of as-cast Al-Mg-Si-Mn alloys

Microstructures of as-cast Al-Mg-Si-Mn alloys with and without Sc and Zr were investigated by optical microscopy, scanning electronic microscopy(SEM) and energy dispersion spectrum analysis. Addition of 0.2%-0.4% Sc can refine the grain size and change the growth morphology from dendritic to fine equi-axial crystal. The higher the addition of Sc, the finer the as-cast grain size. The tensile strength is increased by more than 30% with 0.4% Sc. Moreover, an addition of 0.1%-0.2% Zr is able to refine grain size and change the growth morphology from dendritic to equi-axial grain too, but less effective. However, Zr is found to increase the ductility of the cast alloys, and the elongation is increased to 11.97% with 0.2% Zr.     

Effect of Rare Earth Sc Addition on Microstructure and Mechanical Properties of an Al-Cu-Mg-Ag Alloy

Al-5.3Cu-0.8Mg-0.6Ag alloys containing 0, 0.1, 0.3 and 0.5 (mass. %) Sc were prepared by ingot metallurgy and thermomechanical treatment. The effect of Sc addition on the precipitation and microstructure of the alloys has been investigated using mechanical testing, optical microscope, scanning electron microscopy (SEM) and transmission electron microscopy (TEM). It has been shown that trace Sc element refines the grains of the casting alloys and the average grain size decreases from 85 μm to 30 μm. Increasi...     

Zn与Mg质量比对热挤压Al-Zn-Mg-Sc显微组织及力学性能的影响

制备了Al-2Mg-0.4Sc、Al-5Mg-0.4Sc、Al-5Mg-2Zn-0.4Sc和Al-5Zn-2Mg-0.4Sc等4种合金并在350℃进行热挤压,通过光学显微镜(OM),X射线衍射(XRD),扫描电子显微镜(SEM)、室温拉伸测试,研究了Zn/Mg比对于Al-Zn-Mg-Sc合金组织与力学性能的影响。结果表明,Zn/Mg比的提高对于铸态晶粒具有细化作用,挤压后发生动态再结晶,晶粒尺寸显著减小,但挤压态晶粒尺寸并未随Zn/Mg比的提高而减小。另一方面,Zn/Mg比的提高使Mg32(Al,Zn)49第二相数量增加,且呈现更明显的网状结构。挤压态Al-Zn-Mg-Sc合金屈服强度随Zn/Mg比的提高而提升,主要由于大量Al3Sc粒子与碎化的第二相呈网状分布于晶界,使第二相强化起到主导作用。     

Nd对Mg-2Ca合金组织和性能的影响

以Mg-2Ca-xNd三元合金为主要研究对象,运用金相分析(OM)、扫描电镜分析(SEM)、能谱分析(EDS)、X射线衍射分析(XRD)及万能拉伸试验机等多种分析和测试手段,系统研究了稀土元素Nd含量对Mg-2Ca-xNd三元合金的显微组织和力学性能的影响.结果表明,随着Nd含量的增加,晶粒变得细小,当Nd含量超过2%时,晶粒又开始变得粗大,并且晶界析出相明显增多,晶内析出大量针状Mg-Nd金属间相.Mg-2Ca-xNd合金的抗拉强度先升高后降低,合金的塑性降低.Mg-2Ca-xNd合金的硬度随着Nd含量的增加而增加.     

时效前冷变形对Al-15Zn-0.5Mg-0.5Sc合金组织及力学性能的影响

对热轧态Al-15Zn-0.5Mg-0.5Sc合金进行固溶+时效和固溶+冷轧+时效处理,利用光学显微镜、扫描电镜、透射电镜和万能力学试验机等研究了各状态合金的微观组织及力学性能。结果表明,冷轧可使饱和Al-Zn固溶体分解,并动态析出Zn相,同时冷轧还促使合金晶粒细化以及位错增殖。人工时效可使合金内析出高密度η′相,而冷轧所导致的高密度位错促进了析出过程并加速了η′相向η相的转变。时效前冷轧可明显优化Al-15Zn-0.5Mg-0.5Sc合金的力学性能,Al-15Zn-0.5Mg-0.5Sc合金经固溶+冷轧+70 ℃人工时效后,其屈服强度和极限抗拉强度分别为413和462 MPa,其强化机理包括细晶强化、位错强化和析出强化。而120 ℃时效会加速位错湮灭,从而削弱位错强化效果。     

Effect of minor Sc and Zr addition on microstructures and mechanical properties of Al-Zn-Mg-Cu alloys

Three kinds of Al-Zn-Mg-Cu based alloys with 0.22%, 0.36%（Sc＋Zr） （mass fraction, %）, and without Sc, Zr addition were prepared by ingot metallurgy. By using optical microscopy, transmission electronic microscopy and scanning electron microscopy, the effects of microalloying elements of Sc, Zr on the microstructure of super-high-strength Al-Zn-Mg-Cu alloys related to mechanical properties were investigated. The tensile properties and microstructures of the studied alloys under different heat treatment conditions were studied. The addition of minor Sc, Zr results in the formation of Ala（Sc,Zr） particles. These particles are highly effective in refining the microstructures, retarding recrystallization, pinning dislocations and subboundaries. The strength of Al-Zn-Mg-Cu alloys was greatly improved by simultaneously adding minor Sc, Zr, meanwhile the ductility of the studied alloys remains at a higher level. The 0.36%（Sc＋Zr） alloys gain the optimal properties after 465 ℃/h solution and 120 ℃/24 h aging. The increment of strength is mainly due to strengthening of fine grain and substructure and precipitation ofAl3（Sc, Zr） particles.     

High-throughput study of binary thin film tungsten alloys

Combinatorial magnetron co-sputtering from elemental sources was applied to produce W-alloy thin film composition spread materials libraries with well-defined, continuous composition gradients (film thicknesses between 1 and 2.5 μm). Three systems were studied: W-Fe (0–7 at.%), W-Ti (0–15 at.%) and W-Ir (0–12 at.%). High-throughput characterization of the materials libraries comprised of chemical, morphological and microstructural analyses. Scanning electron microscope investigations revealed that the films have a columnar structure of inverted cone-like units separated by voided boundaries, with a strong correlation to the alloying element content. Significant morphological changes occurred with an increase in the amount of the added element; W films with lower at.% of the alloying element had higher density and tighter grain boundaries, altering towards an increased amount of voids as the concentration of the alloying element increased. Electron backscatter diffraction scanning was used to determine microstructural components (grain size, grain shape, texture evolution), in dependence on the concentration of the alloying element.     

稀土元素Dy对Mg-2Zn-0.5Zr生物镁合金组织与性能的影响

通过拉伸试验、浸泡实验、电化学测试、扫描电镜(SEM)以及光学显微镜(OM)等方法研究了Dy含量对Mg-2Zn-0.5Zr-xDy生物镁合金微观组织、耐腐蚀性能和力学性能的影响。结果表明:随Dy含量的增加,合金的晶粒尺寸逐渐变小,第二相逐渐增多且主要沿晶界分布,合金的平均腐蚀速率先降低后升高,合金的力学性能先升高后降低;当Dy含量为1.5 mass%时,合金的耐蚀性能和综合力学性能均最好,平均腐蚀速率从未添加稀土元素时的1.28 mm/a降为0.92 mm/a,抗拉强度和伸长率分别为154 MPa和8.6%。     

Mechanical properties of squeeze-cast Al-7Si-0.3Mg alloys with Sc-modified Fe-rich intermetallic compounds

Iron (Fe) has a low solid solubility in aluminum(Al), and it usually forms Fe-rich intermetallic compounds.Scandium (Sc) is an element that can act as a grain refiner,modify the eutectic silicon and change the morphology of Fe-rich intermetallic compounds at the same time. The present work was conducted to study the effect of Sc on the mechanical properties of Al-7Si-0.3Mg. The alloy was prepared by squeeze casting at two levels of Fe (0.2 and 0.4 wt%) and three levels of Sc (0 wt%, 0.2 wt% and 0.4 wt%). Sc is found to increase the mechanical properties of the alloy, including its hardness, yield strength and ultimate tensile strength. At 0.2 wt%Fe, adding Sc increases the strength while maintaining good elongation.At 0.4 wt%Fe, adding Sc increases the strength but decreases the elongation slightly. The distributions and morphologies of intermetallic compounds and eutectic silicon affect the elongation. Both Fe-rich intermetallic compounds and Sc-rich intermetallic compounds act as crack initiation sites. The 0.2 wt% Fe+0.2 wt% Sc alloy has the lowest amount of these intermetallic compounds,and eutectic silicon is small and fibrous. So, it has the highest elongation.     

Effect of Ca addition on soft magnetic properties of nanocrystalline Fe-based alloy ribbons

The effect of Ca addition on the magnetic properties of a nanocrystalline Fe-based alloy was investigated. A small amount of Ca (0.06 wt%) was added to the Fe-based alloy, which was then melt spun to fabricate thin ribbons with a thickness of ∼30 μm. These ribbons were heat treated to obtain a nanocrystalline structure with a grain size of ∼10 nm, and the crystallization behavior was studied to optimize the grain structure. The characteristics of the ribbon alloys were analyzed using a B-H meter, a 4-point probe, a transmission electron microscope (TEM), and a scanning electron microscope (SEM). As a result, the optimum permeability and minimum core loss were obtained for the alloy containing Ca, when annealed at 520 °C for 1 h. The analyses revealed that a reduced core loss could be attributed to the high electrical resistivity and suppressed grain growth, which were caused by the Ca element distributed along the grain boundary. Based on the results, Ca addition to Fe-Si-B-Nb-Cu base nanocrystalline alloy was very effective in controlling the grain size, minimizing the eddy current loss, inducing an improved magnetization behavior, and reducing the core loss.     

不同温度时效后Ni-20Cr-18W-1Mo合金晶界偏聚及力学性能研究

采用扫描电镜(SEM)、透射电镜(TEM)、电子探针(EPMA)和高温力学试验机等手段,研究了不同时效温度(200-800 °C)对Ni-20Cr-18W-1Mo高温合金的元素晶界偏聚和力学性能的影响。结果表明,硫、磷元素的晶界偏聚临界时间随时效温度升高而降低;时效温度对元素在晶界和晶内的成分分布有显著的影响;实验合金的抗拉强度和延伸率随时效温度升高而降低。分析发现,硫、磷元素在晶界中的含量随时效温度升高而增大直至两者分别在650和400 °C时达到峰值,是合金在200-600 °C区间内力学性能降低的重要原因。     

微量Sc对2A14铝合金轮毂组织与性能的影响

采用铸锭冶金及等温复合锻造方法,制备了含Sc的2A14铝合金轮毂锻坯,研究了Sc对锻坯组织与性能的影响。结果表明,Sc含量提高至0.3%时,2A14铝合金的晶粒得到明显的细化,大部分晶粒呈等轴晶状态。添加Sc提高了2A14铝合金的伸长率,但其抗拉强度明显降低,使其低于400MPa,原因在于添加Sc后,大量消耗2A14铝合金中的Cu元素,导致强化相θ′-Al2Cu体积分数减少。但Sc能有效抑制合金中的再结晶,减小轮毂锻坯各部位的性能差异,并提高合金的耐热性能。