粉末冶金Cu-Cr合金在0.1MPa纯氧气中的氧化

研究了具有均匀两相组织的粉末冶金Ｃｕ－２５Ｃｒ和Ｃｕ－５０Ｃｒ合 ０．１ＭＰａ氧气中的氧化。与组织不均的铸态Ｃｕ－Ｃｒ合金相似,氧化后两种成分的粉末冶金Ｃｕ－Ｃｒ合鑫匀形成了复杂的混合氧化膜,但未形成连续的Ｃｒ２Ｏ３层。而经机械合经法获和的铬颗粒大小在１μｍ左右的Ｃｕ－２０Ｃｒ合金,氧化时则形成了连续的Ｃｒ２Ｏ３层。档见,在二元双相合金中,合 氧化行为与合金的组织形态,大小和分布密切相关。     

THE OXIDATION OF A TWO-PHASE Cu-50Cr ALLOY IN AIR AT 70O ─900℃

Ｃｕ－５０Ｃｒ合金在７００－９００℃空气中的氧化结果表明,合金的氧化动力学在７０和８００℃遵循抛物线速度规律,在９００℃其瞬时抛物线速度常数随时间而降低。合金氧化外层膜是ＣｕＯ和Ｃｕ２Ｏ,内层膜由氧化铜和尖晶石型氧化物为基并嵌有Ｃｒ颗粒组成,Ｃｒ表面有Ｃｒ２Ｏ３和Ｃｕ２Ｃｒ２Ｏ４膜。９００℃的氧化膜与基体金属界面粘可观察到连续的Ｃｒ２Ｏ３层。合金未形成Ｃｒ的选择性外氧化。     

机械合金化Cu-Cr合金在0.1MPa纯氧气中的氧化

采用机械合金化法制备了两相颗粒极细的Ｃｕ－Ｃｒ与Ｃｕ－４０Ｃｒ合金,研究其在７００￣８００℃,０．１ＭＰａ纯氧气中的氧化。ＭＡＣｕ－２０Ｃｒ及ＭＡＣｕ－４０Ｃｒ合金２４ｈ氧化后均形成了连续的Ｃｒ２Ｏ３层,这主要由于两相颗粒的细化,加快了Ｃｒ颗粒的溶解,缩短了Ｃｒ的扩散距离,从而有效地促进Ｃｒ２Ｏ３层的形成。     

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。     

Cu-Cr-Ni合金在800℃,0.1 MPa纯氧气中的氧化

研究了Ｃｕ－２０Ｃｒ－２０Ｎｉ和Ｃｕ－２０Ｃｒ－４０Ｎｉ两种合金在８００℃,０．１ＭＰａ纯氧气中的氧化行为,结果表明,Ｃｕ－２０Ｃｒ－２０Ｎｉ合金的氧化动力学遵循近似的抛物线规律,而Ｃｕ－２０Ｃｒ－４０Ｎｉ合金的瞬时抛物线速度常数随时间而降低,两种合金生成组织复杂的氧化膜,外层是一连续的ＣｕＯ层,内层是Ｃｕ２Ｏ、ＮｉＯ和Ｃｒ２Ｏ３组成的混合区,其中Ｃｕ２Ｏ基体上分布着少量未氧化完全的Ｃｒ颗粒,这种     

微晶化对Ni-5Cr-5A1合金氧化产物的影响

利用磁控溅射在Ｍ－５Ｃｒ－５Ａ１（原子分数,％）合金上制备与基体相同成分的微晶涂层．获得的涂层在 １０００℃空气中进行了氧化实验．结果表明, ２００ ｈ氧化后涂层表面生成了分层结构的氧化膜：外层为ＮｉＯ和ＮｉＡ１２Ｏ４,内层为连续致密的α－Ａ１２Ｏ３．微晶化使得Ｎｉ－Ｃｒ－Ａ１系三元合金表面生成一层连续Ａ１２Ｏ３所需的Ｃｒ、Ａ１含量大大降低．     

微晶化对Ni-5Cr-5Al合金氧化产物的影响

利用磁控溅射在Ｎｉ－５Ｃｒ－５Ａｌ（原子数,％）合金上制备与基体相同成分的微晶涂层,获得的涂层在１０００℃空气进行了氧化实验。结果表明,２００ｈ氧化后涂一成了分层结构的氧化膜：外层为ＮｉＯ和ＮｉＡ１２Ｏ４,内层为连续致密的α－Ａ１２Ｏ３。微晶化使得Ｎｉ－Ｃｒ－Ａｌ系三元合金表面生成一层连续Ａ１２Ｏ３所需的Ｃｒ、ＡＬ含量大大降低。     

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。     

TiAlCr涂层对TiAl金属间化合物抗高温氧化性能的影响

研究了溅射Ｔｉ－５０Ａｌ－１０Ｃｒ涂层在８００－１０００℃对ＴｉＡｌ金属间化合物抗高温氧化性能的影响。结果表明,ＴｉＡｌ合金由于形成Ａｌ２Ｏ３和ＴｉＯ２的混合氧化物而表现出较差的抗高温氧化性能,而ＴｉＡｌＣｒ层由于形成粘附性了的Ａｌ２Ｏ３膜而大大提高了ＴｉＡｌ的恒温及循环氧化性能,经９００℃１０００ｈ长时间氧化。ＴｉＡｌＣｒ涂层对ＴｉＡｌ合金仍能提供很好的防护,涂层和基格结合我孔洞及裂纹出现,表现     

微晶化对高温合金K38G在CO气氛中腐蚀的影响

研究了高温合金Ｋ３８Ｇ在８５０－１０００℃下ＣＯ气氛中的腐蚀以及微晶化对高温合金Ｋ３８Ｇ在ＣＯ气氛中腐蚀的影响。结果表明：铸态Ｋ３８Ｇ合金在ＣＯ气氛中表面形成Ｃｒ２Ｏ３，ＴｉＯ２和Ｃｒ７Ｃ３，合金发生严重的内腐蚀，腐蚀动力不基本符合抛物线规律；     

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.