电沉积Ni-Co涂层在960℃空气中的氧化行为

采用直流电沉积工艺,通过调节电镀液的组成制备Ni涂层和Ni-Co合金涂层.采用热重(TG)分析金属Ni与Ni-Co合金在960 ℃下的氧化行为;采用SEM/EDS、XRD和Raman分析氧化膜的组成和结构.对氧化膜的形貌、组成、晶粒尺寸和氧化机制进行分析.结果表明:Ni金属、Ni-7%Co和Ni-15%Co合金中Ni的氧化速率遵循抛物线定律,而Ni-30%Co合金中Ni的氧化速率遵循三次方定律;合金中Co含量越高,Ni的氧化速率就越快.金属含量分析表明:位于氧化膜下方的合金中Co元素有缺失,而且在位于氧化膜外侧的地方Co元素逐渐聚集.     

电沉积Ni-Co涂层在960°C空气中的氧化行为(英文)

采用直流电沉积工艺,通过调节电镀液的组成制备Ni涂层和Ni-Co合金涂层。采用热重(TG)分析金属Ni与Ni-Co合金在960°C下的氧化行为;采用SEM/EDS、XRD和Raman分析氧化膜的组成和结构。对氧化膜的形貌、组成、晶粒尺寸和氧化机制进行分析。结果表明:Ni金属、Ni-7%Co和Ni-15%Co合金中Ni的氧化速率遵循抛物线定律,而Ni-30%Co合金中Ni的氧化速率遵循三次方定律;合金中Co含量越高,Ni的氧化速率就越快。金属含量分析表明:位于氧化膜下方的合金中Co元素有缺失,而且在位于氧化膜外侧的地方Co元素逐渐聚集。     

低温退火对电刷镀纳米晶Ni-Co合金镀层性能的影响

采用X射线衍射(XRD)、干滑动磨损、电化学分析等方法研究了低温退火(100～500℃)对电刷镀方法制备的纳米晶Ni-Co合金镀层的组织结构、耐磨性、耐蚀性的影响.结果表明:随着退火温度的升高,纳米晶Ni-44.16%Co合金镀层的晶粒尺寸逐渐增大,从原始晶粒尺寸12.7 nm长大到500℃时的微米晶尺寸.合金镀层的显微硬度随退火温度的升高而提高,300℃退火后达到最大值,以后随加热温度的升高而急剧降低.纳米晶Ni-44.16%Co合金镀层的耐磨性300℃退火后最好,500℃以后急剧下降,与镀层显微硬度的变化密切相关.浸泡试验与电化学分析均表明纳米晶Ni-44.16%Co合金镀层在300℃退火后的耐蚀性优于其他温度,300℃以上退火耐蚀性随温度升高而下降.     

Gd含量对砂型铸造Mg-Gd-Y合金组织与性能的影响

通过金相显微镜、扫描电镜、力学性能测试等手段,研究了Gd含量对砂型铸造Mg-Gd-Y合金组织与力学性能的影响,建立了Gd含量与合金中α-Mg平均晶粒尺寸、屈服强度与抗拉强度之间的数学关系,观察了合金断口形貌,分析了合金的断裂行为。随着Gd含量由0增大至12.7%,α-Mg平均晶粒尺寸由112μm减小至54μm,合金的屈服强度由64.9MPa提高至174.3 MPa,抗拉强度由157.5MPa提高至221.2MPa,伸长率由21.3%降低至0.9%。当Gd含量为10.2%时,合金具有最佳的强度与塑性(σ0.2=140.0 MPa,σb=196.1 MPa,δ=3.3%)。     

GWN751K镁合金组织和性能研究

采用OM,SEM,TEM,XRD等手段,研究了不同状态的GWN751K镁合金的组织和性能。结果表明:铸态合金主要由基体和网状共晶组织构成,σb=215MPa,σ0.2=187MPa,δ=3.5%,DSC曲线存在明显的低熔点吸热峰;经过535℃,16h热处理,共晶组织分解,晶界残留富Mg-Y相,晶粒尺寸明显长大,合金的力学性能有所改善,σb=240MPa,σ0.2=189MPa,δ=10%,DSC曲线低熔点吸热峰消失;合金经过挤压后,发生动态再结晶,力学性能显著提高,σb=320MPa,σ0.2=260MPa,δ=18%,最主要的原因是挤压后合金中存在高密度位错以及细小的晶粒,可显著提高合金的强度和塑性;经过时效后,合金的平均断裂强度达到400MPa以上,但塑性明显降低。铸态合金二次裂纹主要存在于晶界的共晶组织中,535℃,16h热处理以及挤压后的合金二次裂纹主要是在晶粒内部。     

退火对新型锆合金组织与性能的影响

采用扫描电镜(SEM)、电子背散射衍射(EBSD)、X射线衍射(XRD)、透射电镜(TEM)和万能试验机等,研究真空退火对新型Zr-Nb-O-Cu锆合金微观组织与力学性能的影响。结果表明:在580℃、3 h退火条件下,合金的平均晶粒尺寸为2.5μm,晶粒为等轴晶,退火前后均存在■和■两种织构,但基面织构强度有所降低。第二相颗粒在晶内和晶界呈弥散分布,为体心立方(BCC)结构的β-Nb相与密排六方(HCP)结构的Zr-Nb-Fe相,尺寸集中在30～150 nm之间。相对于原材,退火后合金沿轧制方向(RD)和垂直方向(TD)的屈服强度(σ_s)及抗拉强度(σ_b)均下降,试样均韧性断裂。3个方向的应变硬化指数(n)与塑性应变比(r)差异明显。晶粒与第二相的尺寸、织构等因素对力学性能有重要影响。     

挤压Mg-Y-Ni-Co合金的显微组织和力学性能

采用光学显微镜(OM)、扫描电子显微镜(SEM)、透射电子显微镜(TEM)、X射线衍射仪(XRD)和万能试验机，研究了挤压Mg-2.19Y-0.66Ni-0.76Co(摩尔分数，%)合金板材的显微组织和力学性能。结果表明：铸态合金主要由α-Mg基体、晶内14H-LPSO相、分布在晶界的18R-LPSO、Mg Y(Co,Ni)₄及少量弥散的富Y相组成。均匀化过程中合金发生由晶界的18R-LPSO相向晶内的14H-LPSO相的相转变。挤压后合金发生动态再结晶，晶粒显著细化，并形成弱的基面织构，第二相碎化并沿挤压方向分布。拉伸测试结果显示，挤压合金表现出优异的强塑性匹配，其室温的屈服强度(σ_TYS)、极限抗拉强度(σ_UTS)和断裂伸长率(ε)分别为277.2 MPa、199.3 MPa和32.77%。该合金表现出良好的强度和塑性平衡(采用极限抗拉强度断裂伸长率的乘积值表达塑性：σ_UTS×ε=9.08 GPa·%)，其室温下高的拉伸强度主要是由于晶粒细化和LPSO相强化，而良好的延展性主要归因于晶粒细化和织...     

冲头式挤压铸造ZA43合金组织和性能的研究

研究了工艺参数、变质和热处理对冲头式挤压铸造ZA43合金组织和性能的影响。结果表明:控制工艺参数可获得高塑性的ZA43合金(δ5=22％,σb=385 MPa)。变质处理使铸件组织分布更趋于均匀,性能更稳定,B-Ti变质的效果好于RE变质。经过320℃固溶处理可获得高强度(σb=485 MPa,δ5=13％),选择250℃热处理则获得良好的综合性能(σb=470MPa,δ5=16％)。     

Al-12.5Si-3Cu-2Ni-0.5Mg铸造合金热处理工艺设计

采用相图计算软件Pandat建立了Al-xSi-3Cu-2Ni-0.5Mg系合金、Al-12.5Si-xCu-2Ni-0.5Mg系合金平衡相图及Al-12.5Si-xCu-2Ni-0.5Mg合金相含量随温度变化曲线,结合DSC曲线对Al-12.5Si-3Cu-2Ni-0.5Mg铸造合金的热处理工艺进行了设计.结果表明:利用Pandat相平衡热力学软件计算平衡相图,结合DSC曲线来设计Al-12.5Si-3Cu-2Ni-0.5Mg合金热处理工艺是可行的:确定获得最佳室温和高温力学性能的热处理工艺为500℃×2h淬火+215℃×4h空冷;热处理后其室温力学性能平均值为σb=356MPa、δ=0.7%,高温力学性能(350℃)平均值为σb=139 MPa、δ=3.5%.     

热处理对Mg-Gd-Y-Zr合金组织和力学性能的影响

采用拉伸、硬度、显微组织观察等方法,研究了不同热处理条件对Mg-Gd-Y-Zr合金组织和力学性能的影响。结果表明,铸态Mg-Gd-Y-Zr合金经固溶处理后其塑性提高,δ5提高40%;挤压可以明显改善合金的强度和塑性,相比铸态,σb提高25%,σ0.2提高30%,δ5达到14.9%;时效可使挤压态合金的强度得到进一步提高,峰时效时,σb达到420MPa,σ0.2达到310MPa,但塑性有所降低,δ5降低至7.5%。     

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.     

电化学噪声数据处理方法概述

综述了常见的电化学噪声数据处理方法,介绍了直流趋势剔除、统计分析、快速傅立叶变换(FFT)法计算功率谱密度(PSD)以及小波变换处理电化学噪声信号的基本过程,并阐释了各种数学处理及所得参数的物理意义。