用径迹显微照相技术测定Mo对硼在Ni中扩散的影响SCIEI

本文建立了通过脱硼处理用径迹显微照相技术测量硼在合金中扩散系数的新方法。该法灵敏度高,简捷可靠。实验发现,Ni中加入0.5％Mo对硼的扩散影响不大;而加入3％Mo则有使硼的矿散激活能降低,频率因子减小,在900—1250℃的温度范围内有加快硼扩散的作用。     

DIFFUSION OF BORON IN Fe-BASE AND Ni-BASE ALLOYS

用径迹显微照相技术（ＰＴＡ）测定和研究了９００－１２００℃范围内面心立方０４ＭｎＮｂＢ，２５ＭｎＴｉＢ，Ｆｅ－３０％Ｎｉ－Ｂ和Ｎｉ－Ｂ合金以及体心立方Ｆｅ－３％Ｓｉ－Ｂ合金中硼的扩散系数，得到了相应的扩散常数Ｄ＿０和扩散激活能Ｑ的值．实验表明：实际合金中硼的扩散速度与早期文献报道有较大差距，在体心立方结构的Ｆｅ－３％Ｓｉ－Ｂ合金中硼的扩散速度比面心立方结构的钢中快很多，γ－Ｆｅ中加入Ｎｉ可使扩散速度明显增加     

硼在铁基及镍基合金中的扩散

用径变显微照相技术测定和研究了９００－１２００℃范围内面心立方０４ＭｎＮｂＢ，２５ＭｎＴｉＢ，Ｆ３－３０％Ｎｉ－Ｂ和Ｎｉ－Ｂ合金以及体心立方Ｆｅ－３％Ｓｉ－Ｂ合金中硼的扩散系数，得到了相应的扩散常数Ｄ０和扩散激活能Ｑ的值，实验表明：实验合金中硼的扩散速度与早期文献报道有较差距，在体心立方结构的Ｆｅ－３％Ｓｉ－Ｂ合金中硼的扩散度比面心立方结构的钢中快很多，γ－Ｆｅ中加入Ｎｉ可使扩散速度明显增加。     

THE DISTRIBUTION OF BORON IN LOW ALLOY CAST STEELS

研究了Mn-Mo-B-RE系低合金铸钢中硼的偏析和在均匀化、正火、调质热处理过程中硼分布的变化,以及含硼量、稀土元素加入和钢中Mo等合金元素对硼分布的影响.硼在铸钢中有明显的偏析倾向,并随含硼量的增加而加剧;经通常的均匀化处理后,铸钢中硼分布的均匀性受Mo偏析的强烈影响.在特定的条件下,会产生沿奥氏体一定结晶学平面的硼相析出,或沿晶界形成粗大连续网状的硼相,导致脆断.试验还显示稀土元素有保护硼的良好作用.     

低合金铸钢中硼的分布

研究了Mn-Mo-B-RE系低合金铸钢中硼的偏析和在均匀化、正火、调质热处理过程中硼分布的变化,以及含硼量、稀土元素加入和钢中Mo等合金元素对硼分布的影响.硼在铸钢中有明显的偏析倾向,并随含硼量的增加而加剧;经通常的均匀化处理后,铸钢中硼分布的均匀性受Mo偏析的强烈影响.在特定的条件下,会产生沿奥氏体一定结晶学平面的硼相析出,或沿晶界形成粗大连续网状的硼相,导致脆断.试验还显示稀土元素有保护硼的良好作用.     

ZG40MnB铸造低合金钢的熔炼工艺

钻机、泥浆泵中的曲轴、齿轮较多,选用的材料为ZG40MnB,其化学成分和性能要求见表1、表2。此钢属于铸造低合金钢,硼的资源丰富,价格相对低廉,可部分取代铸造低合金钢中的贵金属（Ni、Cr、Mo）,加入硼后大大提高铸件的淬透性。在铸造低合金钢中硼的质量分数一般为0．001％～0．005％,但生产中发现当叫（B）达上限以后,钢中就会出现硼化物沿晶界析出（即与奥氏体脱离共格关系）,严重损害钢的冲击韧度,造成钢的脆性增高,出现“硼脆”。为防止该现象的发生,应严格控制钢中硼含量,以取中下限为宜。     

Al2O3/Mo纳米粉末模压成形烧结及其动力学

对Mo和Al 2 O 3/Mo纳米粉末进行模压成形,研究纯Mo和Al 2 O 3/Mo压坯在1700~2000℃温度范围内的等温烧结过程,并结合烧结模型分析材料烧结过程中的动力学;利用SEM和TEM分析复合材料的显微组织。结果表明：压坯密度与Al2O3的加入量有关,高温烧结时Al2O3/Mo复合材料的致密度高于纯Mo的致密度;在Al2O3/Mo复合材料烧结过程中,烧结机制既有体积扩散又有晶界扩散,且随着Al2O3含量的增加,晶界扩散趋势明显;纯Mo和Al 2 O 3体积分数为5%、10%和15%Al 2 O 3/Mo复合材料的烧结激活能分别为254.24、234.04、221.40和164.37 kJ/mol;Al 2 O 3的加入可促进晶粒的均匀化和组织的细化。     

Cr8Mo2SiV钢的渗硼层生长动力学及耐磨性

对Cr8Mo2Si V钢在1123、1173和1223 K分别进行2、4、6、8 h的固体渗硼试验。结果表明,渗硼层组织为齿状形貌,经X射线衍射(XRD)分析,渗硼层由Fe_2B、FeB、Cr_2B和CrB相组成。渗层厚度随着渗硼温度和渗硼时间的增加而增加,渗硼扩散激活能为194 kJ/mol。经显微硬度、磨损试验结果和磨损产物能谱分析,渗硼后试样表层的硬度和耐磨性较渗硼前有显著的提高。     

激光淬火后Cr12MoV钢渗硼层界面形貌与能谱分析

利用热浸渗法对Cr12Mo V冷作模具钢进行渗硼处理,通过激光淬火对渗硼层进行了强化处理,用SEM、EDS、XRD对渗硼层表面-界面形貌、化学元素分布和物相进行表征,分析了激光淬火对渗硼层组织和性能的影响。结果表明,激光淬火后Cr12Mo V钢渗硼层表面孔洞减少,降低了剥落的可能性;激光淬火后渗硼层产生了Fe-Cr化合物和Fe2B新相,仍以Fe B相为主,有利于减少渗硼层脆性;元素未发生大量扩散,富碳层仍然存在,但组织得到细化,韧性和强度有所提高;激光淬火时孔洞中Si元素溶于奥氏体中,分布更均匀,Cr与Fe结合增强了渗硼层结合强度。     

稀土Dy在等离子W-Mo-Dy共渗中的动力学行为

采用等离子渗金属技术在碳钢表面形成W-Mo共渗层和W-Mo-Dy共渗层,利用origin数值软件、菲克第二定律、阿累尼乌兹公式分析W、Mo、Dy在共渗中的动力学行为。结果表明:在表面0~5μm处,由于稀土Dy的加入使W、Mo原子的扩散系数分别提高了0.94倍和0.62倍,在80μm处,W-Mo-Dy共渗较W-Mo共渗W、Mo原子的扩散速度分别提高了2.87倍和1.07倍;稀土Dy的加入使表面5μm处的W、Mo原子的扩散激活能分别降低7.13和5.19k J/mol,使得90μm处W、Mo原子的扩散激活能分别降低32.20和10.83 k J/mol。在相同工艺条件下,W-Mo-Dy共渗表层控制扩散的主要因素是空位浓度,在次表面稀土Dy可降低W、Mo的扩散激活能。     

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.     

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.     

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。