Si 含量对 FeCoCr0. 5 NiBSix 高熵合金涂层组织结构和耐磨性的影响

目的研究Si含量对激光熔覆FeCoCr_(0.5)NiBSi_x高熵合金涂层组织结构、硬度和耐磨性的影响。方法采用激光熔覆技术,在45钢基体表面制备了不同Si含量的FeCoCr_(0.5)NiBSi_x(x取0,0.1,0.2,0.3,0.4)系列高熵合金涂层,分析涂层的宏观形貌、微观组织及相结构,测试涂层的硬度,通过摩擦磨损实验测试涂层的耐磨性。结果熔覆态高熵合金涂层均由FCC相和M2B相组成,显微组织包括先共晶组织和共晶组织。随着Si含量的增加,FCC相增多,M_2B相减少,共晶组织由蜂窝状到颗粒状,然后消失。高熵合金涂层的平均硬度随着Si含量的增加而先降低后增加,FeCoCr_(0.5)NiBSi0.3的硬度值最小(613HV),FeCoCr_(0.5)NiBSi_(0.4)的硬度值最高(820HV)。高熵合金涂层的磨损体积随着Si含量的增加而先增大后减小,FeCoCr_(0.5)NiBSi_(0.3)的磨损体积最大(0.00406mm3),FeCoCr_(0.5)NiBSi0.4的磨损体积最小(0.00233mm3)。结论随着Si含量增加,涂层的M2B相减少,共晶组织逐步消失,耐磨性则先降低后提高。耐磨性能最好的是FeCoCr_(0.5)NiBSi_(0.4)高熵合金涂层。     

超声滚压强化对CoCrFeMnNiM(M=Ti,Mo)高熵合金激光熔覆层耐磨性的影响EI北大核心CSCD

CoCrFeMnNi高熵合金较低的硬度和较差的耐磨损性能限制了其在表面工程领域的应用。利用激光熔覆技术制备强化的CoCrFeMnNiM(M=Ti,Mo)高熵合金熔覆层,并通过超声表面滚压(USRE)技术强化熔覆层表面。采用XRD、FSEM、EDS、AFM、显微硬度计和摩擦磨损试验机等研究USRE处理对高熵合金激光熔覆层的微观组织、表面形貌、力学性能和摩擦学性能的影响。结果表明:CoCrFeMnNiTi高熵合金激光熔覆层由面心立方(FCC)结构的固溶体相和TiC原位析出相组成,CoCrFeMnNiMo高熵合金激光熔覆层仍由单一的FCC固溶体相组成。USRE处理后涂层的相构成均未发生变化,但CoCrFeMnNiMo涂层的晶粒尺寸得到更明显的细化。USRE处理降低了高熵合金激光熔覆层的表面粗糙度,提高了残余压应力和显微硬度,并且USRE处理对CoCrFeMnNiMo涂层的效果提升更加显著。经过相同工艺参数的USRE处理后,CoCrFeMnNiTi高熵合金激光熔覆层的体积磨损率由1.90×10^(-4)mm^(3)/(N·m)降低到0.71×10^(-4)mm^(3)/(N·m);但由于磨损机制的转变和表面脆性的增大,CoCrFeMnNiMo高熵合金激光熔覆层的磨损率反而上升。探讨了超声表面滚压处理对高熵合金涂层的适用性,可为高熵合金涂层耐磨性的强化提供参考。     

激光熔覆FeCoCrNiCux高熵合金涂层的显微组织和摩擦性能

利用激光熔覆技术制备了FeCoCrNiCu_x(x=0,0.5,1)高熵合金涂层,系统地分析了不同Cu含量涂层的微观组织、摩擦性能与磨损机制。结果表明：制备的FeCoCrNiCu_x高熵合金均为单一FCC相固溶体,并存在Cr、Ni(x=0)和Cu(x=0.5,1)偏析。室温下,三种涂层的摩擦因数均略高于基材的;FeCoCrNiCu涂层的加工硬化作用和延展性的提升使得其磨损率相较基材有显著下降。600℃下,FeCoCrNiCu_0.5和FeCoCrNiCu涂层的摩擦性能均有显著提升;FeCoCrNiCu_0.5涂层形成了平整致密的氧化层使得涂层磨损率仅为1.29×10^-4 mm³/N·m;FeCoCrNiCu涂层形成了由硬质氧化物和高韧性合金构成的机械混合层,使得涂层表现出较好的减摩耐磨性能,其摩擦因数仅为0.24。     

放电等离子烧结铁基非晶涂层的滑动与冲蚀磨损性能

目的研究放电等离子烧结的Fe_(48)Cr_(15)Mo_(14)Y_2C_(15)B_6非晶涂层在滑动和冲刷条件下的耐磨性。方法利用放电等离子烧结(SPS)技术,制备Fe基非晶态合金涂层。通过滑动磨损实验和冲蚀磨损试验,分别评价非晶涂层的滑动磨损性能和冲蚀磨损性能,并通过X射线衍射仪和扫描电子显微镜分析非晶涂层的组织结构以及磨损形貌。结果非晶涂层在滑动摩擦条件下,随着载荷由10 N增加至20 N,磨损率由0.089×10~(-3)mm~3/m上升到0.216×10~(-3)mm~3/m,但摩擦系数由0.841减小到0.778。非晶涂层在冲蚀磨损条件下的体积磨损率随着冲蚀角度(30°~90°)的增加,先增大后减小,45°时达到极大值(15.80 mm~3/h)。磨损表面形貌表明,铁基非晶的滑动磨损机制主要是疲劳磨损和粘着磨损,冲蚀磨损机制主要表现为构成涂层的粉末颗粒的脆性剥落。结论与常用AISI 52100轴承钢相比,SPS制备的非晶涂层在滑动摩擦条件下有着显著的低磨损率和低摩擦系数,但在冲蚀磨损条件下的耐磨性能较差。     

激光熔覆FeCoCrxNiB高熵合金涂层的组织结构与耐磨性

为探究Cr元素对高熵合金涂层组织结构和性能的影响,在45钢基体上用激光熔覆方法制备了FeCoCrxNiB高熵合金涂层,采用X射线衍射仪(XRD)、扫描电子显微镜(SEM)、显微硬度和耐磨测试等方法研究了Cr含量对FeCoCrxNiB激光熔覆高熵合金涂层组织结构、硬度和耐磨性能的影响。结果表明:熔覆态高熵合金的组织均由先共晶M2B相和共晶组织(面心立方结构相(FCC)+M2B相)组成。随着Cr含量的增加,共晶组织含量增多,M2B相减少,先共晶硼化物形态呈现不规则颗粒状到树枝状再到条块状的变化,共晶组织形貌由蜂窝状向片层状转变。涂层平均硬度随着Cr含量增加逐渐降低,FeCoCr0.5NiB涂层平均硬度最高为860HV0.2。涂层的耐磨性能与硬度呈正相关关系,即FeCoCr0.5NiB涂层耐磨性最高,FeCoCr3NiB涂层耐磨性最低。     

等离子熔覆(CuCoCrFeNi)95B5高熵合金涂层研究

系统研究了等离子熔覆技术制备(CuCoCrFeNi)95B5高熵合金涂层的组织和力学性能。结果表明:等离子熔覆过程中的快速凝固条件有利于抑制涂层中金属间化合物的析出,涂层具有fcc和bcc有序固溶体结构。涂层的硬度为6.53GPa,弹性模量为213 GPa。(CuCoCrFeNi)95B5高熵合金涂层具有良好的耐磨性,其相对耐磨性为Q235钢的2.3倍;其主要磨损机理为切削与犁沟机制。     

激光沉积CoCrFeNiSi-(Al,Ti)非等原子比高熵合金涂层腐蚀行为研究

目的 研究Al、Ti元素对激光沉积CoCrFeNi系高熵合金涂层耐蚀性能影响,并对影响程度进行比较。方法 采用激光沉积技术在316L不锈钢表面制备CoCrFeNiSi0.5、CoCrFeNiSi0.5Al0.5、CoCrFeNiSi0.5Ti0.5、CoCrFeNiSi0.5Al0.5Ti0.5等4种成分的高熵合金涂层,并通过X射线衍射仪(XRD)、金相显微镜(OM)、场发射扫描电镜(FESEM)以及电化学工作站等设备对高熵合金涂层凝固组织形貌、微观组织形貌、微区成分分布、耐腐蚀性能等方面进行分析研究。结果 激光沉积CoCrFeNiSi0.5高熵合金涂层物相由单一面心立方(FCC)相构成;CoCrFeNiSi0.5Al0.5高熵合金涂层的主要物相变成体心立方(BCC)相,并形成沿晶界网状分布的Cr3Si相;CoCrFeNiSi0.5Ti0.5高熵合金涂层的主要物相仍为FCC相,但枝晶间区域内形成G相(Ni16Ti6Si7),枝晶内区域形成长条状Cr15Co9Si6相;CoCrFeNiSi0.5Al0.5Ti0.5高熵合金涂层的主要物相为BCC相,枝晶间区域G相含量较CoCrFeNiSi0.5Ti0.5合金涂层有所降低,枝晶内区域形成弥散分布的方形纳米Fe3Al相。激光沉积CoCrFeNiSi-(Al,Ti)非等原子比高熵合金涂层在0.5 mol/L H2SO4溶液中的耐蚀性大小依次为CoCrFeNiSi0.5Ti0.5>CoCrFeNiSi0.5Al0.5Ti0.5>CoCrFeNiSi0.5>CoCrFeNiSi0.5Al0.5。浸蚀后,CoCrFeNiSi0.5高熵合金涂层以均匀腐蚀为主,CoCrFeNiSi0.5Al0.5涂层产生严重的晶间腐蚀,CoCrFeNiSi0.5Ti0.5涂层主要为枝晶间区域的点蚀,CoCrFeNiSi0.5Al0.5Ti0.5涂层枝晶间区域的点蚀程度明显高于CoCrFeNiSi0.5Ti0.5涂层,且枝晶内区域的纳米第二相颗粒发生脱落。结论 在酸性溶液环境中,相较于Al元素,Ti元素可更有效地提升激光沉积CoCrFeNi系高熵合金涂层的耐蚀性能。     

氩弧熔覆AlxCoCrFeCuNi高熵合金涂层组织与耐磨性

目的 利用氩弧熔覆技术在45钢表面制备出AlCrFeCoCuNi高熵合金涂层，改善其耐磨性能。方法 采用机械球磨方式将Al、Cr、Fe、Co、Cu、Ni粉均匀混合，预涂敷在45钢表面，利用氩弧熔覆技术制备出不同Al物质的量之比的高熵合金涂层。采用X射线衍射仪、扫描电子显微镜及能谱分析仪分析涂层的物相及显微组织，利用显微硬度仪测试涂层表面及截面的显微硬度。采用摩擦磨损试验机测试涂层的摩擦系数及磨损率，分析涂层的耐磨性能。结果 Al_xCrFeCoCuNi高熵合金涂层物相主要包括面心立方(FCC)相和体心立方(BCC)相，当Al物质的量之比小于0.5时，涂层由FCC相构成；当Al物质的量之比为1.0～2.0时，涂层由BCC+FCC相构成；当Al物质的量之比达到2.5时，涂层仅存在BCC相。Al_xCrFeCoCuNi高熵合金涂层组织由等轴晶、柱状晶及白色的晶界构成，且较为致密。Al物质的量之比的增加使得涂层的显微硬度提升，当Al物质的量之比为2.5时，涂层最高硬度为710 HV0.5。在相同磨损条件下，Al_xCrFeCoCuNi...     

不同载荷对HVOF 喷涂AlCoCrFeNi 高熵合金涂层摩擦学性能的影响

目的 提高深地钻探钻具关键零部件的抗磨性能。方法 采用超音速火焰喷涂技术(HVOF)制备AlCoCrFeNi高熵合金涂层。采用X射线衍射仪对高熵合金粉末和涂层的相组成进行研究,采用扫描电子显微镜对高熵合金粉末及涂层的微观结构进行分析,使用维氏显微硬度计测得涂层的显微硬度,采用摩擦磨损试验机对涂层在不同载荷下的磨损行为进行研究。采用SEM和EDS对磨痕表面进行分析,采用XPS技术分析磨痕元素成分,利用三维白光干涉形貌仪测量涂层的磨损体积和表面粗糙度。结果 HVOF喷涂AlCoCrFeNi高熵合金涂层结构致密,相结构为BCC相,显微硬度达(536±34)HV0.2,约为35CrMo钢基体[(278±20)HV0.2]的2倍。随着载荷的增加,涂层的摩擦系数减小、磨损率增大。相同载荷下(6 N),涂层的磨损率约为基体的41%。HVOF喷涂AlCoCrFeNi高熵合金涂层的磨损失效机制为,低载荷下(2 N)主要为氧化磨损伴随着轻微的磨粒磨损;高载荷下(4、6 N)受到反复剪切应力出现疲劳磨损。结论 HVOF喷涂AlCoCrFeNi高熵合金涂层具有良好的抗磨性能,可以有效减轻磨损,有望应用于深地钻探钻具关键零部件的表面防护。     

铬铁原矿粉掺杂制备CrFeNiSiAl0.5高熵合金涂层及其组织性能

目的 以40Cr钢为基体,制备掺杂铬铁原矿粉的CrFeNiSiAl0.5高熵合金涂层,提高其硬度与耐磨性.方法 在Cr、Fe、Ni、Al、Si纯金属粉末中掺杂铬铁原矿粉,矿粉有效原子数分数为0％、5％、10％、15％时,采用激光熔覆技术,在40Cr钢基体上制备CrFeNiSiAl0.5高熵合金涂层.利用X射线衍射仪、金相显微镜、扫描电子显微镜,表征高熵合金涂层的物相结构及微观组织.利用硬度计、磨粒磨损机,对涂层的硬度及耐磨性能进行表征.结果 不含铬铁原矿粉时,高熵合金涂层为单一的BCC相,铬铁原矿粉为10％时,出现FCC相.高熵合金涂层微观组织以胞状树枝晶为主,涂层与结合区存在明显分界,与基体呈良好的冶金结合.不含铬铁原矿粉时,高熵合金涂层平均硬度值为643.5HV;铬铁原矿粉为15％时,涂层平均硬度值为838.1HV,是基体的3.4倍.磨损率随铬铁原矿粉占比的增加而降低,铬铁原矿粉有效原子数分数为15％时,磨损率约为0.14 mg/mm2,耐磨性能最好.结论 在40Cr钢基体上成功制备出了以铬铁原矿粉为掺杂组元的高熵合金涂层,铬铁原矿粉的掺入,提升了CrFeNiSiAl0.5高熵合金涂层的硬度与耐磨性.     

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。