退火工艺对铜包钢线界面扩散和结合强度的影响

采用双铜带压接法制备铜包钢线,研究了铜包钢线的退火热处理工艺,探讨了退火温度和时间对铜-钢复合界面扩散和结合强度的影响。结果表明,随着铜包钢线退火温度的升高和时间的延长,扩散层厚度增加,界面结合强度提高。与保温时间相比,退火温度对其影响较大。退火温度为750℃,保温2h后界面结合效果最佳,继续升高温度和延长时间,界面扩散层厚度和结合强度几乎不变。利用扩散方程计算Fe和Cu原子的扩散激活能和扩散常数,确定了扩散常数与退火温度的关系。综合考虑铜包钢线扩散层厚度与结合强度的关系及生产实际要求,得到铜包钢线的最佳退火工艺为750℃保温2h。     

覆铜热处理对Fe80Si9B11非晶铁芯软磁性能的影响:一种改善非晶铁芯温度分布的方法

Fe基非晶合金材料是目前非晶合金中应用最广泛的体系,它具有优异的软磁性能.通过退火处理消除内应力,是提高软磁性能的关键工艺.本工作研究了以快速升温的方式进行退火处理时,Fe80 Si9 B11非晶铁芯内外缠绕铜带对其软磁性能的影响.结果表明,采用合理的非晶/铜厚度比、保温温度及时间,利用铜良好的导热性强化传热,使得温度场更均匀、非晶铁芯不同位置矫顽力差异降低,提升了非晶铁芯的初始磁导率,进而提高热处理效率和软磁性能.     

超薄铜铝复合电缆带的制备及其力学性能研究

针对电缆带以铝节铜的市场需求和超薄铜铝复合板带制备技术缺乏的现状,提出了包含叠轧的多道次累积轧制复合工艺,同时采用快速在线退火工艺成功制备了厚度为0.12 mm的超薄铜铝复合电缆带,并对其不同道次和不同退火工艺下的拉伸力学性能进行了分析.研究表明:采用高温短时在线热处理可以达到低温长时退火处理的效果;超薄铜铝复合带的力学性能对厚度特别敏感;改变初始坯料状态和降低中间退火温度可以改善最终复合带的力学性能.     

冷拉拔铜包铝细丝的退火工艺与组织性能研究

研究了冷拉拔铜包铝细丝合理的退火工艺及其对材料力学性能、铜包覆层组织及界面扩散层厚度的影响规律.结果表明:铜包铝细丝的最佳退火工艺为300℃×60min.低于200℃退火时,铜包铝细丝铜包覆层处于回复阶段,细丝强度从冷拉态的361MPa急剧下降到236MPa,延伸率略有降低;300℃退火后,铜包覆层的再结晶完成,细丝的抗拉强度下降至约152MPa,延伸率升到最高,达到16.3%;400℃退火后,铜包覆层晶粒显著长大,界面处生成脆性金属间化合物,延伸率急剧下降.界面扩散层的厚度随退火温度和保温时间的增加而增大,当退火温度低于300℃时,扩散层厚度随退火时间增加缓慢;当退火温度高于350℃后,扩散层厚度快速增大.延伸率随扩散层厚度的增加先升高后降低,当界面扩散层厚度为2μm时,铜包铝细丝的延伸率最高.     

热处理对磁控溅射制备氧化铬涂层的结构及力学性能的影响

本文采用射频反应磁控溅射技术制备氧化铬涂层并在不同温度及不同的保温时间内进行热处理,通过X射线衍射、纳米压痕、摩擦磨损测试仪等研究温度及保温时间对涂层结构、表面形貌、硬度、弹性模量、耐磨性及涂层与基体间的结合力进行研究.研究表明低于其晶化温度(400℃)进行退火对其结构影响不大,其力学性能没有明显提高,而在高于其晶化温度(500℃)进行退火,其结构变化比较明显,同时其力学性能显著提高,其硬度从初始态的12.3 GPa提高到26GPa,相同试验条件下的磨损量也显著降低,从初始态的1.1×10-3 mm3降低到1×10-5 mm3.涂层与基体之间的结合力随着退火温度的提高、保温时间的延长有明显的改善.保温时间对其结构影响不大,但对其表面形貌有一定的影响,在低于晶化温度延长保温时间表面平均粗糙度降低,而高于晶化温度延长保温时间表面平均粗糙度增加.     

铜在碳钢中扩散及其对碳钢耐腐蚀性的影响

用水溶液电沉积法在碳钢表面电镀铜并进行高温扩散退火,用Den-Broeder法计算铜在碳钢中的扩散系数,研究了铜在碳钢中的扩散行为及其对碳钢耐腐蚀性的影响。结果表明,铜在碳钢中的扩散主要沿晶界进行,铜的扩散抑制了热处理过程中碳钢晶粒的长大。铜在碳钢中的扩散系数为1.11×10-16～3.03×10-11 cm2/s,扩散系数随着退火温度的提高而升高,随着铜浓度的提高而降低。铜在碳钢高温奥氏体区中扩散所需的激活能为126～167 kJ/mol,在高于低温铁素体+奥氏体混合区中激活能为90～108 kJ/mol。通过铜在碳钢中的扩散制备的Cu-Fe梯度材料,具有优良的耐腐蚀性。     

两道次成形过程中拉伸速度及热处理对2A12-O铝合金晶粒尺寸的影响

目的研究铝合金2A12材料在两道次变形过程中拉伸量、拉伸速度及热处理参数对材料晶粒尺寸的影响规律。方法进行了2A12-O铝合金板的"预拉伸-退火-再拉伸-淬火"两道次成形过程。当两次拉伸量相等,总拉伸量不大于20%时,研究了拉伸速度、退火温度、淬火保温时间与试验后晶粒尺寸的关系。结果在拉伸总量较小的情况下,拉伸速度和各热处理参数对材料最终晶粒尺寸的影响较大;当拉伸总量增大到某临界值时,拉伸速度和热处理参数的影响明显减小,各参数下的晶粒尺寸在总拉伸量相同的情况下趋于一致。结论获得了拉伸总量、拉伸速度、退火温度和淬火保温时间等成形及热处理参数对2A12-O铝合金板材晶粒尺寸的影响规律,为该材料成形及热处理过程中的晶粒尺寸控制提供了依据。     

Ag-15Cu-10Au-2Ni合金的显微组织与性能

通过高真空感应熔炼制备Ag-15Cu-10Au-2Ni合金,对其塑性变形以及热处理后的显微组织、力学、电学性能进行了研究。研究结果表明,该合金由富银相和富铜相组成,Ni元素主要固溶在富铜相中;合金的加工强化效果明显,95%变形量合金的硬度达到201 Hv(铸态为90 Hv),抗拉强度达到744 MPa;650℃退火1 h后合金延伸率达到31.8%,硬度与铸态的相近;随退火温度增加合金电阻率先降低后增加,350℃退火1 h后合金的电阻率为最小(3.98μΩ·cm),这是合金低温区退火出现有序相变所致。     

β-FeSi_2材料的高压-热处理合成研究

采用高压技术结合热处理成功地获得了β-FeSi2材料。采用X射线衍射仪分析了退火时间等实验参数对Fe-Si合金相变的影响,借助扫描电子显微镜考察了样品退火后的微观形貌。结果表明在850℃的条件下保温保压30min后淬冷,生成以α-FeSi2、ε-FeSi为主的Fe-Si金属间化合物,随着热处理时间延长β-FeSi2逐渐增多。     

退火处理对AZ31B镁合金薄板组织及性能的影响

研究了AZ31B镁合金薄板不同温度、时间退火处理后的组织和性能。结果表明,镁合金薄板经退火处理后,强度略有下降,伸长率明显提高;在250℃退火保温30min可获得晶粒尺寸为3～5μm的细晶组织,且薄板的综合性能较好;热处理对镁合金薄板的各向异性没有明显作用。     

Al-Cu-Fe QUASICRYSTALLINE PHASE FORMATION BY MECHANICAL ALLOYING

Al-Cu-Fe alloys were prepared from elemental powders in a high-energy planetary ball mill. A sequence of solid state reactions resulting in quasicrystal (QC) phase formation takes place during heating of the as-milled powder. These reactions were studied by both differential scanning calorimetry and x-ray diffraction methods. Mechanically alloyed powders were consolidated by cold and hot pressing, as well as by explosive compaction. After annealing at sufficiently high temperatures, the consolidated samples are single-phase QC, except the ones consolidated by explosion. The high reactivity of the as-milled alloys causes the appearance of high porosity of the consolidated samples after the annealing.     

Laser–arc hybrid welding of high-strength steel and aluminum alloy joints with brass filler

The laser–tungsten inert gas hybrid welding method was adopted to realize the welding process between Q460 high-strength steel and 6061 aluminum alloy. The influence of the dual heat source on the mechanical properties and microstructure of the welded joints are discussed. In addition, the effects of including a copper–zinc interlayer on the microstructure, elemental distribution, and mechanical properties of welded joints are also studied. The results show that the mechanical properties of the welded joints are influenced by the relative heat inputs of the two heat sources and the Cu-Zn interlayer. The braze welded joint fabricated without a Cu-Zn interlayer fractured at an Al-Fe intermetallic compound (IMC) layer formed at the interface, whereas the braze welded joint fabricated with a Cu-Zn interlayer fractured at an Al-Cu IMC layer formed at the interface. Comparisons show that the maximum tensile shear load of the brazed welded joint with the Cu-Zn interlayer was increased by about 20% relative to that formed without the interlayer. The formation of Al-Fe IMC layer in the deep penetration joint was inhibited by the combined effect of the dual heating sources and the Cu-Zn interlayer.     

Grain growth behavior of nanocrystalline Inconel 718 and Ni powders and coatings

Nanocrystalline Inconel 718 and Ni powders were prepared using two approaches: methanol and cryogenic attritor milling. High velocity oxy-fuel (HVOF) spraying of milled Inconel 718 powders was then utilized to produce coatings with a nanocrystalline grain size. Isothermal heat treatments were carried out to study the thermal stability of the methanol milled and cryomilled powders, as well as the HVOF-derived coatings. All nanocrystalline Inconel 718 powders and coatings studied herein exhibited significant thermal stability against grain growth by maintaining a grain size around 100 nm following annealing at 1273 K for 60 min. In the case of the cryomilled nanocrystalline Ni powders, isothermal grain growth behavior was studied, from which the parameters required for the prediction of the microstructural evolution during a non-isothermal annealing were acquired. The theoretical simulation of grain growth behavior of nanocrystalline Ni during non-isothermal annealing conditions yields results that are in good agreement with the experimental results.     

Effect of Grain Size on Phase Transformation and Photoluminescence Property of the Nanocrystalline ZrO_2 Powders Prepared by Sol-Gel Method

Nanocrystalline zirconia （ZrO2） powders were prepared by a sol-gel process followed by annealing treatments from 500 to 1200 ℃. Phase transformation, microstructural features and photoluminescence properties were characterized by X-ray diffraction, transmission election microscopy and photoluminescence spectra, respectively. The results show that both monoclinic phase and tetragonal phase exist in the nanocrystalline ZrO2 powders at annealing temperature in the range of 500-900 ℃, and the concentration of monoclinic phase increases with increasing the annealing temperature. Tetragonal phase is totally transformed to monoclinic phase when annealing temperature is up to 900 ℃. The average grain size of the powders also increases when annealing temperature increases. Two emission peaks centered at 390 nm （named as /390） and 470 nm （named as /470） exist in the photoluminescence spectra, and the intensity ratio of /390 to /470 decreases with increasing annealing temperature. The grain size is proposed to be responsible for the phase transformation in the nanocrystalline ZrO2 powders.     

Structural transition and atomic ordering of Ni49.8Mn28.5Ga21.7 ferromagnetic shape memory alloy powders prepared by ball milling

The Ni_49.8Mn_28.5Ga_21.7 powders of micro-scale irregular equiaxial particles are prepared by ball milling method, and characterized by XRD, DSC and SEM techniques. The powders are found to contain disordered fct structure. Upon heating to high temperatures, the crystal structure of the as-milled powder is found to evolve from disordered fct to disordered bcc and then to a Heusler-type structure sequentially. The critical temperature for the transition from the bcc phase to the Heusler phase is 360 °C. This phase transition process is also a disorder–order transition. An atomic ordering model similar to the grain nucleation and growth is established to explain the annealing temperature dependence of the phase transformation temperature.     

软磁复合材料中铁粉纯度与工艺条件的研究

为生产高性能的电机铁芯,软磁复合材料(Soft Magnetic Composite,SMC)通常以高纯高压缩性铁粉为原料,如果能用较低纯度铁粉取代高纯铁粉,将使生产成本大大降低。本文以3种不同纯度铁粉为原材料,通过在不同工艺条件下压坯密度及表面显微硬度的变化,来表征铁粉纯度对压坯密实程度及加工硬化程度的影响。结果表明:铁粉纯度、杂质元素种类及含量、铁粉颗粒形貌均影响粉末压坯密度。较低纯度铁粉的压坯在500℃氮气中退火30 min,硬度迅速降低30%;而相同条件下高纯铁粉的压坯表面硬度基本不变。当热处理温度达到再结晶温度时,再结晶过程可使硬度降低近50%。     

Magnetic and catalytic properties of Cu0.5Zn0.5Fe2O4 nanocrystallite powders

Cu0.5Zn0.5Fe2O4 nanocrystallite powders (average size 13 nm) were synthesized from Cu-Zn spent catalyst (fertilizers) industries and ferrous sulfate wastes formed during iron and steel making. Cu-Zn catalyst (22.4% Cu and 26.4% Zn) was chemically treated with sulfuric acid at temperature 80 degrees C for 1 hr for the complete dissolving of copper and zinc into sulfate solution, then the produced solution was mixed with stoichiometric ratio of ferrous sulfate and the mixture was chemically precipitated as hydroxides followed by hydrothermal processing. The parameters affecting the magnetic properties and crystallite size of the produced ferrites powder e.g., temperature, time, and pH were systemically studied. X-ray diffraction analysis was used in order to determine the average crystallite size and phase identifications of the produced powder. The magnetic properties were studied by vibrating sample magnetometry. The results showed that the average crystallite size of the powder decreased for the ferrites powder formed at 150 degrees C and then increased by increasing the temperature to 200 degrees C. Interestingly, the saturation magnetization (Bs), remanent magnetization (Br) and coercive force (Hc) were 25.03 emu/g, 0.71 emu/g, and 4.83 Oe, respectively at hydrothermal temperature 150 degrees C for 24 hr and changed to 16.38 emu/g, 0.3864 emu/g, and 5.2 Oe at 150 degrees C and 72 hr. The produced nanoferrite powders are used for studying the catalytic activity of CO conversion to CO2 at different temperatures, pH and times. The maximum conversion (82%) is obtained at temperature 150 degrees C for 24 hrs and pH 12.     

Rietveld analysis of the effect of annealing atmosphere on phase evolution of nanocrystalline TiO2 powders

The structural evolution of nanocrystalline TiO2 was studied by X-ray diffraction (XRD) and the Rietveld refinement method (RRM). TiO2 powders were prepared by the sol-gel technique. Post annealing of as-synthesized powders in the temperature range from 500 degrees C to 800 degrees C under air and argon atmospheres led to the formation of TiO2 nanoparticles with mean crystallite size in the range of 37-165 nm, based on the Rietveld refinement results. It was found that the phase structure, composition, and crystallite size of the resulting particles were dependent on not only the annealing temperature, but also the annealing atmosphere. Rietveld refinement of the XRD data showed that annealing the powders under argon atmosphere promoted the polymorphic phase transformation from anatase to rutile. Field emission scanning electron microscopy (FESEM) was employed to investigate the morphology and size of the annealed powders.     

Surface modification of spherical NdFeB magnetic powders by a fluid-bed nickel electrodeposition

The spherical NdFeB magnetic powders were coated with Ni using a fluid-bed electrodeposition device. The oxidations of rich Nd phase or Fe phase were restrained after Ni coating. After annealing at 300 °C for 30 min, the magnetic properties of both coated and uncoated magnets were decreased. However, the Ni-coated powders showed better magnetic properties than the uncoated powders after the annealing. The compressive strength of bonded magnets improved after annealing due to enhancement of the adhesion between the adhesive and the surface of the magnetic powders.     

电脉冲快速退火对铁基非晶合金性能的影响

采用大电流交流脉冲对非晶Ｆｅ７８Ｂ１３Ｓｉ９合金进行了去应力退火。初步探讨了电脉冲加热对加热速率和该合金内应力释放、退火脆化以及最终软磁性影响的基本规律。结果表明：电脉冲加热可以得到远高于常规退火的加热速率，选择合适工艺参数可使非晶合金内应力释放９０％，软磁性（Ｈ＿ｃ和Ｂ＿ｓ）达常规退火后的９５％以上，与此同时使合金的延性（断裂应变ε＿ｆ）维持在０．９以上，从而有望实现非晶合金磁性与延性的合理配合。