微量Sc对2195铝锂合金应变时效态的显微组织和力学性能的影响

采用拉伸试验机、光学金相显微镜、透射电镜、扫描电镜等设备研究了添加微量Sc对2195铝锂合金应变时效态的显微组织和拉伸性能的影响。结果表明：微量Sc加入后能生成细小弥散Al3(Sc，Zr)质点，起到抑制再结晶的作用；微量Sc的加入既促使合金晶内析出的T1相分布更弥散均匀，又能使亚晶界和晶界上析出的T1相变得细小，几乎不出现明显的晶界无析出带，因而可在不降低合金强度的前提下有效地改善其塑性。     

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.     

Effects of minor Sc on microstructure and mechanical properties of Al-Zn-Mg-Zr alloy welded joint

Two kinds of AI-6.0Zn-2.0Mg-0.12Zr and AI-6.0Zn-2.0Mg-0.2Sc-0.12Zr alloy plates were prepared by ingot-metallurgy. The alloy plates with 3 mm thickness were welded by argon shield welding method, and the mechanical properties and microstructures of the two welded joints filled with AI-Mg-Sc welding wire were studied comparatively. The results show that firstly, minor Sc can raise the mechanical properties of the Al-Zn-Mg-Zr base alloy greatly. The reason for the increment is the fine grain strengthening, precipitation strengthening and the substructure strengthening caused by Al3（Sc, Zr）. Secondly, η phase （MgZn2） and grain size in the heat-affected zone of the alloy without Sc become coarse obviously, the η＇ phase （MgZn2） in the heat-affected zone of the alloy with Sc becomes coarse also, but the grain size has no visible change. Al3（Sc, Zr） particles are rather stable and can inhibit the movement of dislocation/land sub-grain boundaries, overaging softening is not serious. Thirdly, adding minor Sc can raise the strength of welded joint remarkably, the tensile strength of alloy with Sc increases from 395 MPa to 447 MPa and the welding coefficient increases from 0.7 to 0.8 as well. The reason for the high strength of welded joint with Sc addition is the fine grain strengthening, precipitation strengthening and the increasing of resistance to thermal cycling softening caused by Al3（Sc, Zr）.     

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

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Microstructure and properties of Al-4Cu alloy containing Sc

The effects of different contents of Sc addition on the microstructures and properties of the Al-4 %Cu alloy were studied by tensile properties measurement, optical microscope, X-ray diffraction analysis, scanning electronmicroscope (SEM) and energy spectrum analysis. The experimental results show that rare-earth element Sc is capable of refining the dendritic structure of the Al-4%Cu alloy, the tensile strength σb and yield strength σ0.2 just increase a little when the content of Sc is lower than 0.2%; when the content reaches 0.3%-0.4%, σb and σ0.2 slightly decrease; but σb and σ0.2 rise again when the Sc content is 0.5%, though both of them are lower than those of theAl-4%Cu alloy without Sc addition. However, Sc addition has little influence on the elongation of the Al-4 %Cu alloy. Adding Sc to the Al-4%Cu alloy, when the amount of Sc is lower than 0.2%, Sc mostly exists in the α(Al)solid solution; when the Sc content is in the range of 0.3%- 0.5%, only a part of Sc exists in the α-Al solid solution, the rest appears in two ways: one is that Sc and Al form Al3Sc which can strengthen the alloy, and the other,Sc interacts with Al and Cu to form AlCuSc phase.     

Effect of minor Sc and Zr on microstructure and mechanical properties of Al-Zn-Mg-Cu alloy

1 Introduction The microstructure and properties of aluminium alloys are strongly affected by adding small quantities of scandium. Minor Sc may improve the temperature of recrystallization and fracture toughness, decrease the sensitivity of stress corrosi…     

Microstructures and mechanical properties of Al-Cu-Mn alloy with La and Sm addition

The effect of single addition of La or Sm on the microstructures and mechanical properties of an Al-Cu-Mn alloy were investigated by microstructure characterization and tensile test.The results show that addition of La or Sm into the Al-Cu-Mn alloy can remarkably increase the density of θ' phase and refine the microstructure,and thus,improves the mechanical properties at room temperature.La addition results in a more considerable increase in the density and refinement of θ' phase than Sm addition.La addition has a more significant contribution on the mechanical properties of the Al-Cu-Mn alloy than Sm addition.in addition,a new phase of Al6Cu6La is formed in the Al-Cu-Mn alloy with La addition.     

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.     

Microstructures and mechanical properties of Al-Mg and Al-Zn-Mg based alloys containing minor scandium and zirconium

1　INTRODUCTIONAddingofminorMn ,Cr ,Ti,B ,Zr ,Sc ,Agintoaluminumalloyscanremarkablychangethemi crostructuresandpropertiesofaluminumalloys[18] .Amongthem ,theeffectofminorScandZrhasre ceivedspecialattention .Onthe 1stInternationalScandiumConferenceheldinMoscowin 1994 ,Rus sianmetallurgistsdescribedtheapplicationprospectofaluminumalloyscontainingScinaerospace ,aviation ,warshipsandnuclearindustry ,whichhasstimulatedmanyindustrialcountries’researchinterestinthiskindofalloys .Atpresent…     

Microstructures and mechanical properties of a welded CoCrFeMnNi high-entropy alloy

The response of the CoCrFeMnNi high-entropy alloy to weld thermal cycles was investigated to determine its applicability as an engineering structural material. Two processes were used: high-energy-density, low-heat-input electron beam (EB) welding and low-energy-density, high-heat-input gas tungsten arc (GTA) welding. Weldability was determined through comprehensive microstructural and mechanical property characterisation of the welds. The welds did not develop solidification cracking or heat-affected zone cracks. The microstructures in weld fusion zones are similar to that in the as-cast materials, consisting of large columnar grains with dendrite. The dendrite arm spacing and the extent of elemental segregation were less in the welds than in the cast ingot, and also were less pronounced in the EB weld than in the GTA weld. Compositional microsegregation between dendritic cores and interdendritic regions of the welds was insignificant. Both welds exhibited slightly higher yield strengths than the base metal. The EB weld possessed comparable tensile strength and ductility to that of the base metal. In comparison, the GTA weld maintained ～80% of the base metal’s tensile strength and 50% of the ductility.     

Effects of minor Sr,Sn and Sc addition on as-cast microstructure and mechanical properties of ZA84 magnesium alloy

The effects of minor Sr, Sn and Sc addition on the as-cast microstructure and mechanical properties of the ZA84 magnesium alloy were compared. The results indicate that addition of 0.1%Sr, 0.5%Sn or 0.3%Sc (mass fraction) to the ZA84 alloy can refine the grains of the alloy. Furthermore, addition of 0.1%Sr to the ZA84 alloy does not obviously change the morphology and distribution of Mg32(Al,Zn)49 phase. However, addition of 0.5%Sn or 0.3%Sc not only refines and modifies the Mg32(Al,Zn)49 phase but also suppresses the formation of Mg32(Al,Zn)49 phase, especially with the addition of 0.3%Sc. Furthermore, addition of 0.1%Sr, 0.5%Sn or 0.3%Sc to the ZA84 alloy improves the tensile properties at room temperature and 150℃, especially with the addition of 0.1%Sr and 0.3%Sc. However, addition of 0.1%Sr is not beneficial to the creep properties, and addition of 0.5%Sn has no obvious influence on the creep properties. Oppositely, addition of 0.3%Sc to the ZA84 alloy greatly improves the creep properties.     

微量Sc对AA7085铝合金组织与性能的影响

通过铸锭冶金工艺,制备含微量Sc的AA7085铝合金。采用金相观察、力学性能测试、扫描电镜及透射电镜分析,研究添加0.3%Sc对基体合金的铸态及锻造态的显微组织和力学性能的影响。结果表明,添加0.3%Sc能细化铸态合金的晶粒,抑制锻造态合金的再结晶,最终提高基体合金的强度和断裂韧性;含0.3%Sc的合金抗拉强度达到562MPa,断裂韧性KIC(S-L)达到34MPa·m1/2。含Sc的AA7085合金的强化机制主要是Al3(Sc,Zr)相引起的细晶强化、亚结构强化和沉淀强化。     

添加微量Sc对Mg-3%Li合金组织与性能的影响

用真空感应熔炼炉制备了Mg-3%Li和Mg-3%Li-1%Sc两种不同成分的合金。对Mg-3%Li-1%Sc合金进行了固溶和时效热处理。分析了添加Sc对合金组织及性能的影响。结果表明,添加1%Sc后,Mg-3%Li合金的晶粒细化,组织更加均匀,经200℃×9h时效热处理后,Mg-3%Li-1%Sc合金的硬度更高,综合力学性能得到提高。MgSc点状相在基体上均匀地弥散析出和晶粒细化是合金强化的主要原因。     

Effects of micro-alloying with Sc and Mn on microstructure and mechanical properties of Al-Mg based alloys

1INTRODUCTIONAluminum alloys containing scandium havemany excellent properties,such as high strengthtogether with high ductility,good neutron-irradia-tion and corrosion-resistance,and superior weld-ability[14],thus can serve as high-performancestructural materials.They are mainly used formanufacturing aerospace,defense and militaryfacilities.However,a critical Sc content must bereachedin the alloys in order to obtain a good per-formance[57],suggesting that a relatively largequantity of Sc…     

2197铝-锂合金的组织和性能

通过力学性能测试和显微组织观察研究了2197合金组织和性能之间的关系.结果表明:2197合金具有中等强度、各向异性小、热稳定性好等特点;该合金在T8状态下能获得最佳的强度和塑性配合,在T6时效状态以析出少量δ'、θ'和T1相联合强化为主;在2197合金的相组成中T1相析出数量不占主导地位,Al6Mn弥散质点的析出有利于减少各向异性;2197合金中Li含量较低,使其呈现较好的热稳定性.     

Effects of Ag addition on mechanical properties and microstructures of Al-SCu-0.5Mg alloy

The mechanical properties and microstructures of Al-8Cu-0.5Mg alloy with and without Ag addition were studied at both room- and elevated-temperatures. The results show that the alloy with Ag is strengthened by a homogeneous distribution of coexistent θ＇ and Ω precipitates on the matrix （001） and （111） planes, respectively, whereas the alloy without Ag by θ＇ precipitates only. The small size and high volume fraction of θ＇ and Ω precipitates in the Ag-containing alloy improve the tensile strength and yield strength, especially those at the elevated temperatures. However, it is also responsible for the decrease in elongation, compared with the alloy without Ag, which is due to the microcracks initiated from the inherent incompatibility between the particles and the AI matrix during deformation.     

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...     

Microstructures and mechanical properties of TiAl alloy prepared by spark plasma sintering

A fine-grained TiAl alloy with a composition of Ti-47%Al(mole fraction) was prepared by double mechanical milling(DMM) and spark plasma sintering(SPS). The relationship among sintering temperature, microstructure and mechanical properties of Ti-47%Al alloy was studied by X-ray diffractometry(XRD), scanning electron microscopy(SEM) and mechanical testing. The results show that the morphology of double mechanical milling powder is regular with size of 20?40 μm. The main phase TiAl and few phases Ti₃Al and Ti₂Al were observed in the SPS bulk samples. For samples sintered at 1000 °C, the equiaxed crystal grain was achieved with size of 100?250 nm. The samples exhibited compressive and bending properties at room temperature with compressive strength of 2013 MPa, compression ratio of 4.6% and bending strength of 896 MPa. For samples sintered at 1100 °C, the size of equiaxed crystal grain was obviously increased. The SPS bulk samples exhibited uniform microstructures, with equiaxed TiAl phase and lamellar Ti₃Al phase were observed. The samples exhibited compressive and bending properties at room temperature with compressive strength of 1990 MPa, compression ratio of 6.0% and bending strength of 705 MPa. The micro-hardness of the SPS bulk samples sintered at 1000 °C is obviously higher than that of the samples sintered at 1100 °C. The compression fracture mode of the SPS TiAl alloy samples is intergranular fracture and the bending fracture mode of the SPS TiAl alloy samples is intergranular rupture and cleavage fracture.     

Effect of Dy addition on microstructure and mechanical properties of Mg-4Y-3Nd-0.4Zr alloy

Minor Dy element was added into a Mg-4Y-3Nd-0.4Zr alloy, and its effects on the microstructure and the mechanical properties at elevated temperatures were investigated. Scanning electron microscope (SEM) and transmission electron microscope (TEM) were used to observe the microstructures. The results indicated that the as-cast eutectic and isolated cuboid-shaped Mg-RE phases were Mg₅RE and Mg₃RE₁₇, respectively, and distributed mainly along grain boundaries. After a solution treatment, the eutectic Mg₅RE phases were dissolved into the matrix, whereas the Mg₃RE₁₇ compound still remained. After peak aging, fine Mg-RE phases were precipitated homogeneously within the matrix of the alloys containing Dy. Dy addition can result in a significant improvement in the tensile strength at both room and elevated temperatures, and a slight decrease in the elongation.     

Effects of Ag addition on mechanical properties and microstructures of Al-8Cu-0.5Mg alloy

1 Introduction Heat-treatment aluminum alloys are required for many structural applications. And great efforts have been made to either improve the mechanical properties of the alloys currently being used or develop a completely new alloy series. The approaches adopted are either alloying modification, or processing modification, or both. The strength of aging-hardenable alloys such as Al-Cu-Mg series relies upon strengthening precipitates that form during aging after quenching. The aging s…