表面施加氧化物薄膜涂层对Fe25Cr5Al合金高温氧化行为的影响

用电沉积－热解方法在合金表面获得了厚度为０．１－０．５μｍ的单一Ｙ２Ｏ３,Ａｌ２Ｏ３或不同Ｙ２Ｏ３含量与Ａｌ２Ｏ３或Ｃｒ２Ｏ３混合的氧化物薄膜涂层,研究了在１１００℃,１０＾４ＰａＯ２的条件下各类ＯＴＦＣ对Ａｌ２Ｏ３形成Ｆｅ２５Ｃｒ５Ａｌ合金恒温氧化和循环氧化行为的影响。     

Ni－18Cr－3．5Al合金在Cl_2－H_2O环境中的高温腐蚀

研究了Ｎｉ－１８Ｃｒ－３．５Ａｌ合金在５６５℃Ｃｌ２－Ｈ２Ｏ混合气氛中的腐蚀行为，并用ＸＰＳ分析了腐蚀产物膜的结构。在高温Ｃｌ２－Ｈ２Ｏ环境中的腐蚀由Ｃｌ２、ＨＣｌ造成的氯化过程和Ｏ２、Ｈ２Ｏ等造成的氧化过程共同引起。在高温Ｃｌ２环境中低含量Ｈ２Ｏ加速腐蚀过程，而高含量Ｈ２Ｏ延缓腐蚀过程。     

Fe—Mn─Al合金的腐蚀性能与钝化膜的研究

应用阳极极化及ＡＥＳ／ＸＰＳ技术,研究了Ｆｅ－３０．８Ｍｎ－８．２Ａｌ奥氏体合金在ｐＨ值为－０．８至１５．３的水溶液中的腐蚀性能,并与Ｆｅ－３０Ｍｎ合金、低碳钢、９％Ｎｉ低温钢及１Ｃｒ１３不锈钢进行对比。在所测试的水溶液中,该合金的腐蚀抗力优于低碳钢和Ｆｅ－３０Ｍｎ合金,与９％Ｎｉ钢相当,但不及１Ｃｒ１３不锈钢。Ｆｅ－３０．８Ｍｎ－８．２Ａｌ合金在１ｍｏｌ／ＬＮａ２ＳＯ个中形成的钝化膜的最表层可能为氢氧化物,而膜的主体由Ｆｅ２Ｏ３、Ｍｎ２Ｏ３及Ａｌ２Ｏ３组成。     

渗铝NiAl－20％Fe金属间合金的高温热腐蚀

本文研究了在９５０℃空气中，表面涂Ｎａ_２ＳＯ_４盐膜的条件下，ＮｉＡｌ，ＮｉＡｌ－２０％Ｆｅ及渗铝后的高温热腐蚀行为。在热腐蚀过程中，ＮｉＡｌ合金表面能形成Ａｌ_２Ｏ_３膜，显示出一定的耐蚀性能。但Ａｌ_２Ｏ_３膜易开裂，Ａｌ_２Ｏ_３膜的溶解及开裂会引发合金发生快速热腐蚀；２０％Ｆｅ的加入则使ＮｉＡｌ合金的耐蚀性能显著变差，合金表面不能形成单一的Ａｌ_２Ｏ_３膜；渗铝处理可以明显提高ＮｉＡｌ－２０％Ｆｅ合金的耐蚀性能，且渗铝涂层的耐蚀性能优于ＮｉＡｌ合金，这与铝化物涂层中的Ａｌ含量较高，Ａｌ_２Ｏ_３膜的开裂倾向较小有关。     

表面涂覆CeO2对Fe—23Cr—5Al合金上Al2O3膜生长应力的影响

研究了表面涂覆ＣｅＯ２对Ｆｅ－２３Ｃｒ－５Ａｌ合金９００℃和１０００℃下形成的Ａｌ２Ｏ３膜生长应力的影响。涂覆ＣｅＯ２增大了合金的氧化速率,促进了Ａｌ２Ｏ３膜的起皱同时也增大了Ａｌ２Ｏ３膜的生长应力。涂覆ＣｅＯ２表面形成的起皱的Ａｌ２Ｏ３膜在冷却过程中剥落量较少;而在真空保温过程中应力不容易释放。认为表面涂覆ＣｅＯ２对Ｆｅ－２３Ｃｒ－５Ａｌ的抗氧化并不能起到改善作用。     

非晶态Fe－W镀层铬酸盐钝化膜耐蚀机理探讨

Ｆｅ－Ｗ非晶镀层经铬酸盐钝化处理，可获得具有装饰效果的含Ｃｒ钝化膜。经测定，孔蚀电位较钝化前正移１．６８Ｖ，明显改善了抗ＣＩ－腐蚀的能力。ＡＥＳ与ＸＰＳ的分析结果表明：钝化膜由内外两层构成，外层为Ｆｅ（ＣｒＯ４）３·Ｃｒ２（ＣｒＯ４）３／Ｃｒ２（Ｃｒ２Ｏ７）３·Ｆｅ（ＯＨ）３／ＦｅＯＯＨ·ＷＯ３·ｎＨ２Ｏ等化合物，内层由Ｃｒ２Ｏ３，ＣｒＯ３，ＣｒＯＯＨ，ＦｅＯ，Ｆｅ２Ｏ３及ＷＯ３组成。钝化膜厚度约为６０ｎｍ。该双层饨化膜有效地阻止了Ｃｌ－对基体金属的腐蚀。     

Ni—18Cr—3.5Al合金在Cl2—H2O环境中的高温腐蚀

研究了Ｎｉ－１８Ｃｒ－３．５Ａｌ合金在５６５℃Ｃｌ２－Ｈ２Ｏ混合气氛中的腐蚀行为，并用ＸＰＳ分析了腐蚀产物膜的结构。在高温Ｃｌ２－Ｈ２Ｏ环境中的腐蚀由Ｃｌ２、ＨＣｌ造成的氯化过程和Ｏ２、Ｈ２Ｏ等造成的氧化过程共同引起。在高温Ｃｌ２环境中低含量Ｈ２Ｏ加速腐蚀过程，而高含量Ｈ２Ｏ延缓腐蚀过程。     

溅射Ni-8Cr-3.5Al纳米晶涂层的抗高温氧化行为

对Ｎｉ－８Ｃｒ－３．５Ａｌ质量分数,％合金及其纳米晶涂层进行了１０００℃空气中高温氧化研究。结果表明：Ｎｉ－８Ｃｒ－３．５Ａｌ纳米晶涂层的抗高温氧化性能优于Ｎｉ－８Ｃｒ－３．５Ａｌ合金。这主要在于Ｎｉ－８Ｃｒ－３．５Ａｌ纳变涂层表面生成了具有分层结构含一连续α－Ａｌ２Ｏ３内层的氧化膜,而Ｎｉ－８Ｃｒ－３．５Ａｌ合金则生成了由Ｃｒ２Ｏ３内氧化物组成的氧化膜。讨论了涂层氧化膜的生成过程。     

Na2SO4沉积盐引起的Ni3Al—Fe的中温区热腐蚀

研究了Ｎａ２ＳＯ４沉积盐引起的Ｎｉ３Ａｌ－Ｆｅ于７００－８２０℃空气中的腐行为，结果表明，Ｎｉ３Ａｌ－Ｆｅ遭受自持性的热腐蚀，热腐蚀的发生似可归因于Ｆｅ与Ｎａ２ＳＯ４反应的产物Ｎａ２Ｏ与Ｎａ２ＳＯ４形成了Ｎａ２Ｏ－Ｎａ２ＳＯ４共晶熔融盐，随中金中Ｍｏ的氧化产物ＭｏＯ３参与电化学阴极还原反应，从而引发合金快速的热腐蚀，此外，熔盐中Ｎａ２ＳＯ４与ＭｏＯ３反应生成的ＳＯ３导致了熔盐的高酸度和合金的内硫化     

Na_2SO_4 INDUCED HOT CORROSION OF Ni_3Al－Fe INTERMETALLIC COMPOUND AT INTERMEDIATE TEMPERATURES

研究了Ｎａ_２ＳＯ_４沉积盐引起的Ｎｉ_３Ａｌ－Ｆｅ于７００一８２０℃空气中的腐蚀行为。结果表明，Ｎｉ_３Ａｌ－Ｆｅ遭受自持性的热腐蚀。热腐蚀的发生似可归因于Ｆｅ与Ｎａ_２ＳＯ_４反应的产物Ｎａ_２Ｏ与Ｎａ_２ＳＯ_４形成了Ｎａ_２Ｏ－Ｎａ_２ＳＯ_４共晶熔融盐，随后合金中Ｍｏ的氧化产物ＭｏＯ_３参与电化学阴极还原反应，从而引发合金快速的热腐蚀。此外，熔盐中Ｎａ_２ＳＯ_４与ＭｏＯ_３反应生成的ＳＯ_３导致了熔盐的高酸度和合金的内硫化，从而进一步加剧了腐蚀的进程。     

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).     

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.     

Theoretical Analysis for the Motion and Temperature of Melt Droplets in Spray Degassing Process

The motion of melt droplets in spray degassing process was analyzed theoretically. The height of the treatment tank in spray degassing process could be determined by the results of theoretical calculation of motion of melt droplets. To know whether the melt droplets would solidify during spraying process, the balance temperature of melt droplets was also theoretically analyzed. Then proof experiments for theoretical results about temperature of melt droplets were carried. In comparison, the experimental results were nearly similar to the calculation results.     

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.