Fe_(86)Zr_5Nb_1B_8和Fe_(86)Zr_1Nb_5B_8非晶纳米晶合金微观结构的研究

对采用单辊快淬法制备Fe_(86)Zr_5Nb_1B_8和Fe_(86)Zr_1Nb_5B_8非晶纳米晶合金薄带在不同温度下进行退火处理。利用X射线衍射仪和扫描电镜研究合金的微观结构。结果表明:Fe_(86)Zr_5Nb_1B_8和Fe_(86)Zr_1Nb_5B_8合金的自由面存在α-Fe相(200)晶面择优取向;随着退火温度的升高,Fe_(86)Zr_5Nb_1B_8和Fe_(86)Zr_1Nb_5B_8合金自由面和贴辊面α-Fe相的平均晶粒尺寸变化比较复杂。     

Fe_(73.5)Cu_1Nb_3Si_(13.5)B_9非晶合金的晶化动力学

用差热分析(DTA)结合X射线衍射(XRD),研究了Fe_(73.5)Cu_1Nb_3Si_(13.5)B_9非晶合金的晶化动力学。结果表明:温度在0～700℃范围内,该合金的晶化相为α-Fe和Fe_2B;α-Fe相晶化表观激活能为452.39kJ/mol,Fe_2B相的晶化表观激活能395.23kJ/mol;两相在晶化初期激活能最小,随晶化量X_c的增加而迅速增大,在α-Fe的体积分数为30％～80％,Fe_2B的体积分数为40％～80％时,呈现极大值。     

Nb对液态激冷Fe_(70)Cr_(18)Mo_2B_9Si_1合金组织及性能的影响

本文对比了液态激冷Fe_(70)Cr_(18)Mo_2B_9_Si_1合金及Fe_(68.5)Cr_(18)Mo_2B_9Si_1Nb_(1.5)合金在不同温度保温后组织及显微硬度的变化情况,分析了Nb对基体晶粒尺寸以及硼化物相M_2B,M_3B_2的化学成分、点阵常数、形核及长大的影响,发现Nb能促进M_3B_2的形核,并降低了M_2B和M_3B_2的长大速率     

铸态Ti-Zr-Ni准晶基合金的室温力学性能

用吸铸法制备出含Ti(Zr)固溶体韧性相的Ti-Zr-Ni准晶合金棒，通过维氏显微硬度测定和单向压缩实验等方法研究了该新型合金的室温力学性能和断裂行为。结果表明：Ti-zr-Ni准晶基复相(α-Ti(Zr) I)合金力学性能良好，维氏显微硬度值接近5.5GPa，断裂强度达到1000MPa，Young’s模量值23-36GPa。其中，Ti60Zr25Ni15合金的室温弹性应变可达4．2％，是Al基准晶合金的4倍。但其室温单向压缩时的断裂方式仍为准解理断裂，属脆性断裂。     

Nb元素对β型Ti-Mo基合金显微组织、力学性能和铸造性能的影响（英文）

为了开发新型的生物医用β型钛合金,设计并采用电弧熔炼方法制备Ti-15Mo-xNb(x=0.5,10和15,质量分数,%)合金,研究添加元素Nb对4种合金显微组织、力学性能和铸造性能的影响。相分析和组织观察结果表明,4种合金均由单一的β相组成,随着Nb含量的增加,合金的显微组织细化。β型Ti-15Mo-xNb合金具有较高的塑性和相当低的压缩弹性模量(18.388~19.365 GPa)。添加Nb元素后,合金的压缩屈服强度增高,随着Nb含量的增加,合金的显微硬度降低。在冷压缩变形后,4种合金均呈现明显的纤维带状组织。4种合金的充型实验表明:添加Nb元素后,合金的充型能力降低,Ti-15Mo合金的充型性能(92.01%)最好。     

添加Mo对Fe-50Al显微组织、有序度和室温力学性能的影响（英文）

研究添加Mo对Fe_(50)Al_(50-n)Mo_n合金(n=1、3、5、7和9,摩尔分数,%)凝固及热处理后的显微组织、位相关系、有序-无序相变温度和室温力学性能的影响。通过X射线衍射分析、扫描电镜和差示扫描量热法对材料进行结构表征,通过压缩试验和显微硬度测试研究其室温力学性能。结果显示,所有合金中均有Mo_3Al颗粒析出,这是因为Mo在Fe-Al基相中的固溶度有限。铸态Fe_(50)Al_(50-n)Mo_n合金在室温下表现出脆性,具有高的屈服强度和有限的断裂应变。与铸态合金相比,热处理后除了Fe_(50)Al_(41)Mo_9合金以外,其他合金的室温力学性能都得到提高。热处理态Fe_(50)Al_(43)Mo_7合金具有最高的断裂应变(25.4%)和抗压强度(2.3 GPa)。     

Ti和Al的交互作用对Nb-Ti-Si-Al合金微观组织和力学性能的影响（英文）

研究高Al含量对合金中Nb-Al金属间化合物形成的影响及2个高Al含量的Nb-Ti-Si-Al合金(A2:Nb-18Ti-14Si-9Al、A4:Nb-21Ti-14Si-9Al)的微观组织和力学性能,其中设计A4合金是为了分析Ti含量变化的影响。结果表明:A2合金由(Nb)、Nb_5Si_3和Nb_3Al_3相组成,而A4合金由(Nb)和Nb_5Si_32相组成。A2和A4合金的室温断裂韧性分别为11.1和10.9 MPa·m~(1/2)。同时对2个合金进行微压痕测试,以表征合金在微观尺度的力学性能。     

汽车用铝合金富铁相形貌研究

由于Al-Si合金优异的机械性能,从而广泛应用于汽车制造业,然而Fe是这类合金中最主要的杂质元素,显著地降低了合金的力学性能。本文运用X射线来鉴别Fe相组织,同时用扫描电镜技术来观察富铁的特征。通过X射线图谱已经证实Al-Si合金显微结构中存在三种富铁相,其为α-Fe(Al_(15)Fe_3Si_2),β-Fe(Al_5FeSi)和δ-Fe(FeSi_2Al_4)。在形态特征上,α-Fe,β-Fe和δ-Fe分别为长针状、汉字状和长块状。并简要分析了针状Fe相孪晶生长过程。     

添加Nb对Zr-4合金在500℃过热蒸汽中耐腐蚀性能的影响

用高压釜腐蚀实验研究了在Zr-4合金成分基础上添加0.1%-0.3%(质量分数)Nb的合金在500℃/10.3MPa过热蒸汽中的耐腐蚀性能,用TEM和SEM分别观察了合金的显微组织和氧化膜断口形貌,结果表明.合金在500℃/10.3 MPa过热蒸汽中腐蚀500 h均未出现疖状腐蚀.完全抑制了疖状腐蚀的产生,这与Nb在αZr中的固溶量较大有关.固溶在αZr中的Nb能抑制疖状腐蚀斑的形核,提高耐疖状腐蚀性能;合金耐均匀腐蚀性能随着Nb含量的增加而降低,这与Nb的添加降低了固溶在α-Zr中的(Fe+Cr)含量有关,也与Zr(Fe,Cr.Nb)_2第二相的析出有关.这2种因素都会加快氧化膜显微组织在腐蚀过程中的演化,促进孔隙和微裂纹的形成.     

钴基合金Co-Al-W-Ta-Nb的显微组织与高低温力学性能

以新型Co基合金Co-9Al-9W-2Ta为基础,分别用4at%、6at%和9at%的Nb元素替代等量的W(分别称4Nb、6Nb、9Nb合金,无Nb添加的称为0Nb合金),研究Nb含量对合金显微组织和高低温力学性能的影响。结果表明:铸态组织由Co基固溶体γ相和γ+Co3Nb共晶组成(Nb可部分被W和/或Ta取代),随Nb含量提高,共晶组织体积分数增大。1200℃/8h固溶+800℃/100h时效处理后,γ中析出尺寸为数百纳米并与之共格的γ’-Co3(Al,W)相或Co3Nb相,显微组织由γ/γ’组织(0Nb)逐步向γ/γ’/Co3Nb组织(4Nb和6Nb合金)和γ/Co3Nb组织转变(9Nb合金)。合金在600℃开始出现反常屈服,反常屈服强度峰值对应温度大约在700℃。     

Effects of Post-weld Heat Treatment on Microstructure,Mechanical Properties and the Role of Weld Reinforcement in 2219 Aluminum Alloy TIG-Welded Joints

In as-welded state, each region of 2219 aluminum alloy TIG-welded joint shows diff erent microstructure and microhardness due to the diff erent welding heat cycles and the resulting evolution of second phases. After the post-weld heat treatment, both the amount and the size of the eutectic structure or θ phases decreased. Correspondingly, both the Cu content in α-Al matrix and the microhardness increased to a similar level in each region of the joint, and the tensile strength of the entire joint was greatly improved. Post-weld heat treatment played the role of solid solution strengthening and aging strengthening. After the post-weld heat treatment, the weld performance became similar to other regions, but weld reinforcements lost their reinforcing eff ect on the weld and their existence was more of an adverse eff ect. The joint without weld reinforcements after the post-weld heat treatment had the optimal tensile properties, and the specimens randomly crack in the weld zone.     

The First Phase of the SRIF Industrialized Base in ＂West Area＂ Has Been Put into Operation

After nearly two years＇ tense construction, the first phase of industrialized base of Shenyang Research Institute of Foundry （SRIF）, located at the Tiexi Casting and Forging Industrial Park in the west of Tiexi District, has now been completed and formally put into operation.     

Thermodynamics Study on the Decomposition of Chromite with KOH

Institute of Process Engineering, Chinese Academy of Sciences, China, has proposed a method for oxidative leaching of chromite with potassium hydroxide. Understanding the mechanism of chromite decomposition, especially in the potassium hydroxide fusion, is important for the optimization of the operating parameters of the oxidative leaching process. A traditional thermodynamic method is proposed and the thermal decomposition and the reaction decomposition during the oxidative leaching of chromite with KOH and oxygen is discussed, which suggests that chromite is mainly destroyed by reactions with KOH and oxygen. Meanwhile, equilibrium of the main reactions of the above process was calculated at different temperatures and oxygen partial pressures. The stable zones of productions, namely, K2CrO4 and Fe2O3, increase with the decrease of temperature, which indicates that higher temperature is not beneficial to thermodynamic reactions. In addition, a comparison of the general alkali methods is carried out, and it is concluded that the KOH leaching process is thermodynamically superior to the conventional chromate production process.     

Influence of Heat Treatment on Damping Behaviour of the Magnesium Wrought Alloy AZ61

The effect of isochronal heat treatments for 1h on variation of damping, hardness and microstructural change of the magnesium wrought alloy AZ61 was investigated. Damping and hardness behaviour could be attributed to the evolution of precipitation process. The influence of precipitation on damping behaviour was explained in the framework of the dislocation string model of Granato and Lücke.     

Effect of Rare Earth Doping on Impedance,Modulus and Conductivity Properties of Multiferroic Composites:0.5(BiLa_xFe_(1-x)O_3)–0.5(PbTiO_3)

The Lanthanum-doped bismuth ferrite–lead titanate compositions of 0.5(Bi LaxFe1-xO3)–0.5(Pb Ti O3)(x = 0.05,0.10,0.15,0.20)(BLxF1-x-PT) were prepared by mixed oxide method.Structural characterization was performed by X-ray diffraction and shows a tetragonal structure at room temperature.The lattice parameter c/a ratio decreases with increasing of La(x = 0.05–0.20) concentration of the composites.The effect of charge carrier/ion hopping mechanism,conductivity,relaxation process and impedance parameters was studied using an impedance analyzer in a wide frequency range(102–106Hz) at different temperatures.The nature of Nyquist plot confirms the presence of bulk effects only,and non-Debye type of relaxation processes occurs in the composites.The electrical modulus exhibits an important role of the hopping mechanism in the electrical transport process of the materials.The ac conductivity and dc conductivity of the materials were studied,and the activation energy found to be 0.81,0.77,0.76 and 0.74 e V for all compositions of x = 0.05–0.20 at different temperatures(200–300 °C).     

Using Finite Element and Contour Method to Evaluate Residual Stress in Thick Ti-6Al-4V Alloy Welded by Electron Beam Welding

This work was to reveal the residual stress profile in electron beam welded Ti-6Al-4V alloy plates(50 mm thick) by using finite element and contour measurement methods.A three-dimensional finite element model of 50-mmthick titanium component was proposed,in which a column–cone combined heat source model was used to simulate the temperature field and a thermo-elastic–plastic model to analyze residual stress in a weld joint based on ABAQUS software.Considering the uncertainty of welding simulation,the computation was calibrated by experimental data of contour measurement method.Both test and simulated results show that residual stresses on the surface and inside the weld zone are significantly different and present a narrow and large gradient feature in the weld joint.The peak tensile stress exceeds the yield strength of base materials inside weld,which are distinctly different from residual stress of the thin Ti-6Al-4V alloy plates presented in references before.     

Microstructures and Tensile Properties of Ultrafine-Grained Ni–(1–3.5) wt% SiC_(NP) Composites Prepared by a Powder Metallurgy Route

Silicon carbide nanoparticle-reinforced nickel-based composites(Ni–Si CNP),with a Si CNPcontent ranged from1 to 3.5 wt%,were prepared using mechanical alloying and spark plasma sintering.In addition,unreinforced pure nickel samples were also prepared for comparative purposes.To characterize the microstructural properties of both the unreinforced pure nickel and the Ni–Si CNPcomposites transmission electron microscopy(TEM) was used,while their mechanical behavior was investigated using the Vickers pyramid method for hardness measurements and a universal tensile testing machine for tensile tests.TEM results showed an array of dislocation lines decorated in the sintered pure nickel sample,whereas,for the Ni–Si CNPcomposites,the presence of nano-dispersed Si CNPand twinning crystals was observed.These homogeneously distributed Si CNPwere found located either within the matrix,between twins or on grain boundaries.For the Ni–Si CNPcomposites,coerced coarsening of the Si CNPassembly occurred with increasing Si CNPcontent.Furthermore,the grain sizes of the Ni–Si CNPcomposites were much finer than that of the unreinforced pure nickel,which was considered to be due to the composite ball milling process.In all cases,the Ni–Si CNPcomposites showed higher strengths and hardness values than the unreinforced pure nickel,likely due to a combination of dispersion strengthening(Orowan effects) and particle strengthening(Hall–Petch effects).For the Ni–Si CNPcomposites,the strength increased initially and then decreased as a function of Si CNPcontent,whereas their elongation percentages decreased linearly.Compared to all materials tested,the Ni–Si CNPcomposite containing 1.5% Si C was found more superior considering both their strength and plastic properties.     

Directional Growth of Tin Crystals Controlled by Combined Solute Concentration Gradient Field and Static Magnetic Field

A new method was introduced to achieve directional growth of Sn crystals. Microstructures in liquid(Pb)/liquid(Sn) diffusion couples were investigated under various static magnetic fields. Results show that the β-Sn crystals mainly reveal an irregular dendritic morphology without or with a relatively low static magnetic field(B0.3 T). When the magnetic field is increased to 0.5 T, the β-Sn dendrites close to the final stage of growth begin to show some directional character. With a further increase in the magnetic field to a higher level(0.8–5 T), the β-Sn dendrites have an enhanced directional growth character, but the dendrites show a certain deflection. As the magnetic field is increased to 12 T, the directional growth of the β-Sn dendrites in the center of the couple is severely destroyed. The mechanism of the directional growth of the β-Sn crystals and the deflection of the β-Sn crystals with the application of static magnetic field was tentatively discussed.     

Quantitative Analysis of the Crystallographic Orientation Relationship Between the Martensite and Austenite in Quenching–Partitioning–Tempering Steels

The orientation relationships(ORs)between the martensite and the retained austenite in low-and medium-carbon steels after quenching–partitioning–tempering process were studied in this work.The ORs in the studied steels are identified by selected-area electron diffraction(SAED)as either K–S or N–W ORs.Meanwhile,the ORs were also studied based on numerical fitting of electron backscatter diffraction data method suggested by Miyamoto.The simulated K–S and N–W ORs in the low-index directions generally do not well coincide with the experimental pole figure,which may be attributed to both the orientation spread from the ideal variant orientations and high symmetry of the low-index directions.However,the simulated results coincide well with experimental pole figures in the high-index directions{123}_(bcc).A modified method with simplicity based on Miyamoto’s work was proposed.The results indicate that the ORs determined by modified method are similar to those determined by Miyamoto’method,that is,the OR is near K–S OR for the low-carbon Q–P–T steel,and with the increase of carbon content,the OR is closer to N–W OR in medium-carbon Q–P–T steel.     

Growth Kinetics of Single Inclusion Particle in Molten Melts

On the basis of the single-particle framework, a new theory on inclusion growth in metallurgical melts is developed to study the kinetics of inclusion growth on account of reaction and collision. The studies show that the early growth of inclusion depends on reaction growth and Brawnian motion collision, and where the former is decisive, the late growth depends on turbulence collision and Stokes＇ collision, and where the former is dominant; collision growth is very quick during the smelting process, lessened in the refining process, but nearly negligible in the continuous casting process.