火车轮对再制造用ER6车轮钢粉末的制备及其性能表征

采用氮气雾化制备火车轮对再制造用ER6车轮钢粉末,并通过激光粒度分析仪、扫描电子显微镜和霍尔流速计等表征手段研究了不同粒径的ER6车轮钢粉末的粒度分布、表面形貌及内部微观组织、流动性和松装密度.结果表明:氮气雾化制备的ER6车轮钢粉末粒径呈正态分布,主要集中在17～158μm之间,中粒径d50≈55μm,粉末球形度较高;随着粉末粒径的减小,粉末表面越光滑,卫星颗粒减少;金属粉末表面和内部组织主要由枝状晶和胞状晶组成,但粒径较小的粉末因冷却速率较高,胞状晶晶粒明显细化且枝状晶数量减少;所制备的ER6车轮钢粉末流动性和松装密度分别在19.22～24.47 s/50 g和4.11～4.43 g/cm3范围内,呈现出良好的稳定性.     

雾化气体压强对2A14铝合金粉末形貌和粒度分布的影响

针对3D打印技术对球形、微米金属粉末的需求,利用超音速气雾化方法制备了2A14铝合金粉末,并系统研究了雾化气体压强对粉末球形度、粒径和粒度分布的影响.结果表明:最佳雾化气体压强为6.0 MPa,该压强下制备的2A14铝合金粉末球形度高,粒度分布窄,平均粒径为32μm,能够满足3D打印的要求.     

Ti-Cu-Ni-Zr块体非晶合金形成能力及其压缩性能

采用铜模铸造法制备了不同直径的Ti40Cu34+xNi16-xZr10(x=0,2,4,5,6)系列合金,并利用X射线衍射(XRD)、扫描电镜(SEM)、差氏扫描量热仪(DSC)研究了合金的相结构、显微组织、热稳定性.结果表明:只有Ti40Cu39Ni11Zr10合金成分可制备出2 mm的全非晶结构,增加制备尺寸到3 mm、4 mm后,有TiCu晶体相析出;玻璃转变温度Tg、晶化温度Tx分别为665 K和712 K,过冷液相区ΔTx为47K.压缩实验表明:Ti40Cu39Ni11Zr10块体非晶合金具有高达1 931 MPa的屈服强度,并伴有0.3%左右微量压缩变形量,塑性变形以锯齿形式出现;Ti40Cu34Ni16Zr10合金具有1.3%的压缩变形量,TiCu相的析出提高了该合金压缩变形量.     

用等离子旋转电极雾化法制备TC4合金粉末的研究

用等离子旋转电极雾化法制备TC4合金粉末,利用金相显微镜和扫描电镜对粉末粒度及形貌进行分析观测;考察了料棒转速工艺参数对粉末粒度的影响,以及不同粉末粒径下氧、氮元素质量分数的变化,并对不同形貌的颗粒成因进行分析和探讨。结果表明,随着合金棒旋转速度增大,TC4球形粉末平均粒度出现减小趋势;粉末体的氧元素质量分数随着粒径减少而增大,而氮元素质量分数则没有显著变化;粉末的表观形貌由于制备时其尺寸大小和所处的位置不同而存在两种形态。     

机械合金化法制备Ti-Zr-Ni-Cu储氢合金

使用行星式球磨机,用机械合金化法制备了Ti60Zr15Ni15Cu10储氢合金.采用X射线衍射仪XRD、示差扫描量热计DSC分析了球磨粉末的物相、晶粒尺寸的变化;采用扫描电子显微镜SEM、能谱EDS分析了机械合金化过程中粉末的形貌和成分;并对球磨粉末进行了P-C-T曲线测量.研究结果表明,粉末晶粒尺寸随球磨时间增加不断减小.球磨120 h粉末含有大量非晶相.粉末颗粒中有明显的冷焊合层状结构.随球磨时间增加,层状结构的层厚不断减小,颗粒中的元素分布趋于均匀,合金化过程中的冷焊合和断裂作用逐渐趋于平衡.合金的最大吸氢量物质的量为1.63%,纳米结构粉末的吸氢量高于非晶结构粉末.     

Mg-Zn-Ca块体非晶合金及其强度可靠性

针对Mg-Ln-TM块体非晶合金脆性大、强度可靠性差等特点,研究了新型Mg-Zn-Ca非晶合金的性能并考察了成分变化对其热稳定性的影响。采用铜模铸造法制备出直径为2mm的Mg_70-xZn_25+xCa₅(x=1、2、3、4)系列非晶合金,利用扫描电镜(SEM)、X射线衍射仪(XRD)、差分扫描量热仪（DSC）以及电子万能试验机分别研究了铸态样品的组织、相结构、热稳定性以及力学性能。实验结果表明：该系列非晶合金的晶化过程分3~4步完成,初始晶化温度随Mg含量的提高而降低,同时对应较高的强度和一定的塑性应变。经Weibull统计分析表明：这4种非晶合金断裂强度的再现性存在差别,其中具有脉络纹断口的合金具有较高的Weibull模量,对应着良好的断裂强度再现性。     

放电等离子烧结参数对Fe_(76)Si_9B_(10)P_5非晶合金致密化及晶化的影响

采用放电等离子烧结(Spark Plasma Sintering,SPS)方法,在不同的烧结温度、保温时间、升温速率和烧结压力下,固结Fe76Si9B10P5非晶粉末。用差式扫描量热仪测定了非晶粉末的过冷液相温区,用X-ray衍射方法分析了放电等离子烧结前后样品的相结构,研究了SPS法烧结参数对Fe76Si9B10P5非晶样品致密化及结晶化的影响,并在非晶粉末的玻璃转变温度以下快速烧结制备了尺寸为Ф15×3 mm的块体非晶合金,致密度达98.7%。     

Nb对Cu基非晶合金热加工及力学性能的影响

为了提高Cu基非晶合金的热加工性能和力学性能,采用铜模铸造法制备了直径为2 mm的Cu47Zr47-xAl6Nbx非晶合金.分别利用X射线衍射仪、扫描电子显微镜、差示扫描量热计和电子万能试验机对Cu47Zr47-xAl6Nbx非晶合金的相组成、显微组织、热力学参数和力学性能进行了研究.结果表明,适量的Nb元素可以提高Cu47Zr47-xAl6Nbx非晶合金的热加工和力学性能.Cu47Zr47Al6非晶合金的过冷液相区和断裂强度分别为53.5 K和1 528 MPa.当Nb元素的原子分数为2%时,Cu47Zr45Al6Nb2非晶合金具有最大的过冷液相区和断裂强度,且可以分别达到69.0 K和1 830 MPa.     

Ce-Al-Ni非晶合金制备及非晶形成能力研究

采用熔体旋淬法制备了Ce75Al25-xNix(x=4,8,16)和Ce68Al17Ni15,Ce73Al15Ni12非晶合金薄带,用X射线衍射(XRD)法表征了合金薄带的相结构,用差示扫描量热法(DSC)测量了合金薄带连续加热过程相变规律,研究了Ce-Al-Ni合金的非晶形成能力与合金成分及相应的非晶形成能力参数(ΔTx,Trg,γ,δ,β,ω)之间的关系.研究结果表明:当Ce的含量一定时,随着合金中Ni原子百分数的增加,合金的非晶形成能力降低;研究还发现Ce-Al-Ni体系具有非常特殊的非晶形成规律,计算评估的用来预测具有强的非晶形成能力的合金成分参数(ΔTx,Trg,γ,δ,β,ω)不能用来表征Ce-Al-Ni合金的非晶形成能力;根据非晶形成能力参数计算的预测具有强的非晶形成能力的合金成分,实验研究不能观察到更好的非晶形成能力.     

退火处理对Ti-Zr-Cu-Be块体非晶合金力学性能的影响

采用铜模铸造法制备了直径为2mm的Ti55-xZr10+xBe27.5Cu7.5(x=0,10,20)块体非晶合金,并对其进行等温退火处理.利用X射线衍射(XRD)、扫描电镜(SEM)、差氏扫描量热仪(DSC)及压缩试验等方法研究了非晶合金的相结构、显微组织和热稳定性,以及退火处理对其力学性能的影响.结果表明:该系列合金在553 K及583 K下保温长达5 h时间内依然表现为非晶态.退火处理后,Ti35Zr30Be27.5Cu7.5合金屈服强度、断裂强度均提到了提高,其中在583 K下保温1 h后屈服强度、断裂强度分别达到了1 921、2 169 MPa;其塑性由处理前的3.47%提高到了6.57%.Ti45Zr20Be27.5Cu7.5合金在退火后其力学性能变化不明显.Ti55Zr10Be27.5Cu7.5合金随着退火温度及保温时间的增加其屈服强度、断裂强度及塑性均明显降低.     

Preparation and microstructure of AI-Ni-Y powder by rapid solidification

1　INTRODUCTIONAluminium basedamorphoushasattractedmoreandmoreattentionforitsgoodmechanicalproper ties[13] .Al basedamorphouswereoftenpreparedbymeltspinningonasinglerollerordoublerollers[4 8] .SincetheglassformingabilityofAlalloyisrelativelylow[9] ,theAl basedamorphouscanonlybepreparedunderhighsolidificationvelocity ,whichresultsinnubAl basedamorphousalloyorfilm(preparedbyionbeamsputtering[10 ] )withorderofμm .Itisverydif ficultforustoproducebulkyAl basedamorphousal loy ,whichalsolimits…     

Characterization of 17-4PH stainless steel powders produced by supersonic gas atomization

17-4PH stainless steel powders were prepared using a supersonic nozzle in a close-coupled gas atomization system. The characteristics of powder particles were carried out by means of a laser particle size analyzer, scanning electron microscopy (SEM), and the X-ray diffraction (XRD) technique. The results show that the mass median particle diameter is about 19.15 μm. Three main types of surface microstructures are observed in the powders: well-developed dendrite, cellular, and cellular dendrite structure. The XRD measurements show that, as the particle size decreases, the amount of fcc phase gradually decreases and that of bcc phase increases. The cooling rate is inversely related to the particle size, i.e., it decreases with an increase in particle size.     

Solidification structures of high niobium containing TiAl alloys

To understand the effect of alloy stoichiometry on the microstructural development and mechanical behavior of γ-TiAlbased materials, it is necessary to have a determination of the phase relationships for the TiAl alloy system near the γ phase field.Cast structures and phases of Ti-(43-47)Al-8Nb-(1-2)Mn (at%) alloys have been studied by using scanning electron microscope and X-ray diffraction. Their solidification path and microstructure development during the solidification were analyzed. The experimental results show that the alloys with different Al contents form different macrostructures and microstructural morphologies. This indicates that the solidification paths are different with different Al contents. The alloy with 43Al forms equiaxed grain structure, and the solidification path is as follows: L → L β→β→α β→α β cores →α2 γ B2 cores. Whereas the alloy with 47Al forms columnar grain structure, and the solidification path is as follows: L → L β→α β L →α γ β cores →α2 γ B2 cores. The β phase is their primary solid phase and can be retained to ambient temperature. The alloy with 43Al solidifies completely into β phase. The peritectic reactions L β→α and L α→γ appear when the Al content increases to 47Al.     

Si_3N_4-doped Zr_(50)Al_(15)Ni_(10)Cu_(25) glassy alloy by mechanical alloying and sintering process

Zr50Al15Ni10Cu25 amorphous powder was synthesized by mechanical alloying.The effect of Si3N4 addition on the crystallization behavior of the alloy during sintering process was studied.Thermal stability of the powders was performed by differential scanning calorimetry(DSC).The phase and microstructure of the powders and bulk specimens sintered were determined by X-ray diffractometry(XRD) and scanning electron microscopy(SEM).The results show that,introducing 0.05%(mass fraction) Si3N4 can enhance the crystallization activation energy of the Zr50Al15Ni10Cu25 amorphous powders,which indicates that Si3N4 addition has hindrance effect on forming crystals from Zr50Al15Ni10Cu25 amorphous powder.However,0.10% Si3N4 results in the decrease of the crystallization activation energy,which makes its crystallization process easy to occur.     

铝粉的粒径和形状对照明剂发光强度的影响

利用激光粒度仪和光效应测试仪测定铝粉的粒径和照明剂的发光强度。研究不同形状和粒径的普通铝粉,以及用化学法细化制备的超细粉对Ba(NO3)2+Al照明剂发光强度的影响。结果表明:照明剂的发光强度随铝粉粒径的减小而增大,非球状铝粉的发光强度大于球状铝粉的发光强度。粒径在小于2μm时发光强度的变化率陡增,粒径在0.6～2.13μm区间发光强度变化率是2.13～4.24μm区间发光强度变化率的4.37倍,表明铝粉超细化至亚微米后可以大幅度提高烟火药剂的发光强度.     

含稀土Er的Al-Zn-Mg合金的组织与性能

为了探讨稀土Er对热处理可强化(沉淀强化)的铝合金系作用,采用铸锭冶金法制备了6种含Er量不同的Al-Zn-Mg合金进行了深入分析.通过硬度测试、拉伸力学性能测试、金相观察、X射线衍射和扫描电镜观察,研究了稀土元素Er对Al-Zn-Mg合金显微组织和力学性能的影响.实验结果表明,稀土元素Er可以显著地细化Al-Zn-Mg合金的铸态晶粒,减小其枝晶网胞,当Er的添加量达到w(Er)=0.7％时,枝晶网胞几乎完全消失,晶粒变得非常细小且分布均匀;对于合金的冷轧态组织以及时效态晶粒也有同样的细化效果;添加Er后,Al-Zn-Mg合金在冷轧态及时效态下的屈服强度(σ0.2)及抗拉强度(σh)都得到了显著的提高,但塑性有所降低;稀土元素Er添加到Al-Zn-Mg合金中,主要与Al相互作用形成了Al3Er相.合金显微组织的细化及合金的强化都与该相的形成和析出有关.     

片状氧化铝粉体的控制合成及表征

研究了碳酸氢铵和硝酸铝在添加剂氟化铵作用下沉淀法合成片状氧化铝粉体,讨论了片状氧化铝粉体的形成机理.通过XRD,SEM对产物进行表征.结果表明氟化铵有效控制了氧化铝颗粒的大小和形貌,改善了氧化铝的结晶.适量加入氟化铵可以获得分布均匀、分散性良好,粒径3-8 μm,厚度0.2-0.3 μm的正六边形片状氧化铝粉体.     

Microstructure and mechanical propertiesof spray-deposited Al-Si-Fe-Cu-Mg alloy containing Mn

Al-20Si-5Fe-3Cu-1Mg alloy was synthesized by the spray atomization and deposition technique. The microstructure and mechanical properties of the spray deposited hypereutectic Al-Si alloy were studied using optical microscopy, scanning electron microscopy, X-ray diffraction, TEM (Transmission Electron Microscope) and HREM (High-resolution Electron Microscope), DSC (Differential Scanning Calorimetry), microhardness measurement, and tensile tests. The effects of Mn on the microstructural evolution of the high-silicon aluminum alloy after extrusion and heat treatment have been examined. The results show that two kinds of phases, i. e. S (Al2CuMg) and σ(Al5Cu6,Mg2), precipitated from matrix and improved the tensile strength of the alloy efficiently at both the ambient and elevated temperatures (300℃). The tensile test results indicate that the spray-deposited Al-20Si-5Fe-3Cu-1Mg alloy has better strength than the powder metallurgy processed Al-20Si-3Cu-1Mg alloy at elevated temperature.