Refining Effect of a New Al3Ti1B1RE Master Alloy on Al Sheets Used for Can Manufacture and Behavior of Rare Earths in Master Alloy

The refining effect of Al3Ti1B1RE master alloy on Al sheets used for pressure can manufacture and the behav-ior of mixed rare earths (RE) in master alloy were investigated with XRD, OM, SEM and EDAX. It is found that the re-fining effect of the refiner on the material has superiority over foreign or domestic Al5Ti1B refiner, and the refiner still re-tains its refining ability for 6 h after adding it to molten Al, thus improving the strength and plasticity of the material re-markably. The excellent refining effect and stability of AlTiBRE refiner result from that RE can lower the surface energy of molten Al and improve the wetting characteristics of molten Al on refinement nuclei such as TiAl3, TiB2, etc., thus giving full play to the effect of heterogeneous nucleation and impeding the congregating tendency of TiB2 phase in molten Al. At the same time, RE gathering in front of solid/liquid interface are also easy to cause composition supercooling in molten Al, thus impeding the growth of α-Al grains and promoting α-Al nucleation on refinement nuclei. In addition, RE also play certain role in purification and grain refinement, or modification, especially their effect of purification can improve the metallurgical quality of AlTiBRE master alloy.     

Effect of Rare Earth on Microstructure of Eutectic A1-2 % Fe Alloy

Effect of La-rich rare earth on eutectic microstructure in A1-2? alloy was studied. When the addition of RE is small, a-A1 phase is in the form of cellular dendrite. With the increase of the addition of RE, the nucleation and growth of a-A1 dendrite are suppressed, and eutectic Al3Fe phase is refined.When the addition of RE gets to 0.6% (mass frac-tion), the size of eutectic Al3Fe increases. In addi-tion, mechanism of the effect of mixed RE on eutectic morphology of A1-2? alloy is explored.     

On Mechanism of The Effect of Rare Earth on Wearability of Nickel Base Self-Fluxing Alloy Spray-Welding Layers

The mechansim of the effect of rare earth(RE)on wearability of spray-welding layers has been investi-gated by adding RE in ppm into Nickel base self-fluxing alloy powder.The test results show that the microalloy-ing effect of RE can refine the structure of spray-welding layers,and change the amount,size,shape and distri-bution of hard phase in spray-welding layers.The wearability of spray-welding layers is increased consequently.     

Effect of Magnetic Field on Solidification Microstructure of Cu-20wt%Nb Alloys and Properties of the In-Situ Deformed Wires

Magnetic field has great impact on the second phase distribution in metal solidification process.In this paper,we have Cu-20wt%Nb alloy remelted and solidified with or without the imposition of magnetic field,to study the effect of magnetic field on the distribution of Nb phase and the properties of deformed wires.Magnetic field has an inhibiting effect on the ripening process of Nb particles,and is benefit to the prolongation of Nb-rich phase in deformed wires.Both the ultimate tensile strength and conductivity in 1 T case is larger than that in 0 T case.     

Effect of RE on the Brittleness of Electrolytic Boronization Coating

The electrolytic coatings of boron and RE-boron on medium carbon steel are carried out in molten salt mix-tures respectively.The brittleness of both coatings has been measured by using sound-emission with the methodof three point bending.Results show that the brittleness of electrolytic boronization coating can be obviously de-creased by addition of RE elements.Meanwhile,the shape of crack and the solid solubility of RE in boride andα-Fe phase are determined,and the effect of RE on the lattice constant of Fe_2B is discussed.From these experi-ments,the authors explain the cause of the brittleness decreasing of electrolytic boronization coating.     

Thermodynamics of Modifying Effect of Rare Earth Oxide on Inclusions in Hardfacing Metal of Medium—High Carbon Steel

The modifying effect of rare earth(RE)oxide on inclusions in hardfacing metals of medium-high carbon steel was investigated by means of thermodynamics,The thermodynamic analsys for inclusion formation shows that RE oxide can be reduced to RE element by carbon,then the RE element can react with oxygen and sulfur to form the RE oxide,RE sulfide and RE oxide-sulfide in hardfacing molten pool.The deoxidization and the desulphurization can be carried otu and the liquid metal can be purified.In addition,RE oxide can also react with sulfur to form RE oxide-sulfide dirdctly.Therefore,the harmful effect of sulfur can be decreased.     

Modification Behavior of Trace Rare Earth on Impurity Phases in Commercial Purity Aluminum

Modifying effect and mechanism of trace rare earth on Fe(Si)-rich impurity phases in commercial purity aluminum were studied with the aids of SEM, EDAX, TEM, etc. It is found that Ce-rich mixed rare earth (RE) is an effective modifying agent, which makes the coarse Fe-rich impurity phases transform into complex compounds of tiny, sphere/short stick form, thus improving mechanical properties of this material; its modifying mechanism is in that RE gathering in front of solid/liquid interface enters into the impurity phases, forming complex (A1FeSiRE) compounds; or is adsorbed in the impurity phases surface, impeding the growth of impurity phases; however, excessive RE will result in the increasing of RE compounds (secondary phases), and plasticity reduction of this material. Therefore, its addition amount should be less than 0.07% (mass fraction).     

Internal Friction in Rail Waist of BNb and BNbRE Steels

The experi ments showed that the inclusions andpearlite of the steel were modified and/or refined ,andthe plasticity ,toughness , wearability as well as theservice life of the rail were obviouslyi mproved by add-ing RE.It was firstlyfoundthat as a result of additionof REinthe steel ,there appeared an obvious inhibit-ing and/or di minishing effect on the fatigue damage ,particularly on both nuclear damage and rail waistdamage[1 ,2]. However , whether the initiation and ex-tension of the residi…     

Toxicity of Lanthanum to Pathogenic Fungi and Its Morphological Characteristics

Rare earth (RE) ,a kind of natural mineral hasbeen used as a beneficial element to crops for quite alongti me . Withthe solution of a series of keytechnolo-gies such as extraction,separation of radioactive ingre-dients ,sanitary toxicology,and environmental safety,China became the first countryto apply commercial REproducts asfertilizer or growthsti mulatorin agriculture ,which produced considerable economic and social ben-efits[1 ,2].RE has been found to have some controllingeffects on many…     

Effect of RE Elements on the Morphology of Carbides and the Impact Fatigue Properties of the Low Cr White Cast Iron

An apparatus of zone melting unidirectional solidification with a steep temperature gradient andan impact fatigue tester were used.The effect of RE elements on the morphology of carbides and the impactfatigue properties of the low Cr white cast iron were investigated.Experimental results showed that the modi-fying effect of RE elements was remarkable on the M3C carbides.With the addition of RE elements in thelow Cr iron,a lot of plate-like carbides were transformed into lath-like and rod-like ones.The higher thecontent of RE elements was,the more was the fraction of the lath-like and rod-like carbides.In the low Crwhite cast iron,the RE modifying agent can efficiently increase the impact fatigue resistance and decrease thecrack growth rate and delay the time of incipient cracking.With the increase of the content of RE elements inthe low Cr cast iron,the impact fatigue resistance increased greatly and the crack growth rate decreased rap-idly.     

高温合金GH4065A的恒温静态氧化行为

研究了新型镍基高温合金GH4065A在650～750℃的静态氧化行为,基于对氧化动力学与氧化产物的分析,探讨了合金的氧化机制.结果表明:采用平均氧化增重速率指标评定GH4065A合金在650～750℃温度范围内均为完全抗氧化级别,试验条件下合金的抗氧化能力与典型涡轮盘材料FGH96、GH4720Li合金相当;合金的氧化产物主要为内层富铝的氧化物颗粒、外侧富铬的氧化物膜及表面金红石型TiO2颗粒,TiO2颗粒在氧化温度超过700℃后开始生成;合金的氧化动力学遵循抛物线型规律,受钛离子与铬离子穿过氧化膜的扩散过程共同控制.     

Influence of yttrium addition on high temperature oxidation resistance of single crystal superalloy

Two experimental single crystal superalloys Y-free alloy and Y-containing alloy were cast in the directionally solidified furnace, while other alloying element contents were basically kept unchanged. T...     

Effects of lanthanum ion-implantation on microstructure of oxide film formed on Co-Cr alloy

Isothermal and cyclic oxidizing behavior of Co-40Cr alloy and its lanthanum ion-implanted samples were studied at 1000 ℃ in the air by thermal-gravimetric analysis （TGA）. Scanning electronic microscopy （SEM） and transmission electronic microscopy （TEM） were used to examine the morphology and structure of oxide film after oxidation. Secondary ion mass spectrum （SIMS） method was used to examine the binding energy change of chromium caused by La-doping and its influence on the formation of Cr2O3 film. laser Raman spectrum was used to examine the stress changes within the oxide film. It was found that lanthanum implantation remarkably reduced isothermal oxidizing rate of Co-40Cr and improved anti-cracking and anti-spalling properties of Cr2O3 oxide film. The reasons for the improvement were mainly that the implanted lanthanum reduced the grain size and internal stress of Cr2O3 oxide and increased high temperature plasticity of the oxide film. Lanthanum mainly existed on the outer surface of Cr2O3 oxide film in the form of fine La2O3 and LaCrO3 spinel particles.     

稀土元素La对GH230合金1000℃抗氧化性能的影响

 对加入稀土La 0～0.087％（质量分数）的GH230合金进行了1000℃恒温氧化实验。实验结果表明:适量La能有效地提高GH230合金的抗氧化能力和增强表面氧化膜的剥落抗力。但当合金中La含量达到0.087％（质量分数）时,合金中析出富La相会降低其氧化抗力。     

Influence of Nanometric Ceria Sol-gel Coating on Oxidation Behavior of Chromium at 1000℃

 Isothermal oxidation behavior of chromium with and without nanometric sol-gel CeO2 coating is studied at 1000℃ in air. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) are used to examine the surface morphology and microstructure of their oxide films. It is found that ceria coating greatly improves the anti-oxidation property of chromium. Laser Raman spectrometer and X-ray diffraction spectrometer (XRD) are also used to study the stress level in oxide films formed on ceria-coated and ceria-free Cr. Secondary ion massive spectrum (SIMS) is used to examine Cr, O and Ce element distribution in depth in oxide films. Results show that nano-ceria application greatly reduces the growing speed and grain size of Cr2O3 film, and his fine grain-sized Cr2O3 film probably has better high temperature plasticity, i.e. oxide film relieves part of the compressive stress by means of creeping. Meanwhile, CeO2 changes the oxide film growing mechanism from predominant cation outward diffusion to anion inward diffusion. XRD and Raman testing results both show the stress declination effect due to nano-CeO2 application, and their discrepancy is analyzed concerning to the rare earth effect.     

含钼铁素体不锈钢的高温氧化行为

 采用增重法研究了排气系统用Type444铁素体不锈钢在1000℃空气中的高温抗氧化性能,并结合X射线衍射(XRD)、扫描电镜(SEM)、能谱分析(EDS)及辉光光谱(GDS)分析技术,对氧化膜的形貌和组成进行了分析。结果表明：Type444铁素体不锈钢在1000℃下连续氧化100h,氧化动力学曲线按照抛物线线型氧化规律变化,氧化激活能为(277. 5±10) kJ·mol-1,表面氧化膜由连续致密的Cr2O3组成,具有良好的高温抗氧化性能。铌和钼元素扩散至Fe2(Nb,Mo) Laves相,其氧化物颗粒会充当沉淀物从氧化膜表面逆扩散至基体和氧化膜界面处的孔洞里,从而降低了其在高温下的氧化速率,提高了抗高温氧化性能。     

铝对HP40合金高温抗氧化性能的影响

 采用增重法研究了w(Al)=5%~10%的HP40合金在1 200 ℃×30 h空气中的抗氧化性能。结果表明,铝可显著提高合金的高温抗氧化性能,而且合金的高温抗氧化性能随铝含量增加而提高。1 200 ℃时,合金氧化增重与氧化时间的关系呈抛物线规律,氧化速率随氧化时间延长而逐渐下降。加入铝,改变了合金氧化膜层的物相组成和致密度,含铝合金的氧化层中含有Al2O3,而且Al2O3量随铝加入量增加而增多。     

铝对抗磨耐热钢抗氧化性的影响

 研究了不同铝含量的Fe 25Cr 20Ni在900 ℃、1000 ℃和1100 ℃的高温氧化行为。其中,Fe 25Cr 20Ni 472Al在900 ℃、1000 ℃和1100 ℃时的平均氧化速度比Fe 25Cr 20Ni分别降低47.14％、58.14％和17.49%。X射线衍射分析结果表明,氧化膜主要为Fe、Cr的氧化物和尖晶石（NiCr2O4、FeCr2O4）,其中在Fe 25Cr 20Ni 472Al合金中检测到了Al2O3。对氧化后试样截面进行扫描电镜观察和能谱分析,结果表明,不含铝以及铝的质量分数为1.68%和7.10%的试样氧化后氧化膜分为两层：即厚度较为均匀,存在较多的破碎、剥落的外层和外层与基体之间的较为致密,但存在空穴的内层;铝的质量分数为4.72 %的试样氧化膜较为致密,基本无剥落,分层现象不明显,生成的Al2O3存在于氧化膜的最外层,有效防止了材料的进一步氧化。     

00Cr25Ni22Mo2N奥氏体不锈钢的高温氧化行为

采用静态增重法研究了00Cr25Ni22Mo2N奥氏体不锈钢在不同温度下的循环氧化动力学曲线.结果表明,00Cr25Ni22Mo2N不锈钢在700℃时的氧化动力学曲线是一条平行于时间轴的直线,这说明其在该温度下氧化反应非常微弱;在800和900℃时的氧化动力学曲线遵循抛物线氧化规律,具有良好的抗氧化性能.利用扫描电镜、能谱分析和X射线衍射对氧化膜的表面形貌、截面形貌和相组成进行研究,发现该钢在3个温度下都生成了致密和黏附性好的保护性氧化膜,700℃生成的氧化膜主要由Cr2O3和Fe2O3组成,氧化膜很薄;800℃生成的氧化膜由Cr2O3、Fe2O3和少量的NiCr2O4、FeCr2O4组成,氧化膜厚度增加;900℃生成的氧化膜由Cr2O3、Fe2O3和NiCr2O4组成,氧化膜厚度进一步增加.认为氧化膜组成和结构是00Cr25Ni22Mo2N不锈钢具有良好抗高温氧化性能的重要原因.     

Effect of cerium addition on oxidation behavior of 25Cr20Ni alloy under low oxygen partial pressure

The influence of Ce addition on the oxidation behavior of 25Cr20Ni alloy at 950 oC under low oxygen partial pressure was inves-tigated. The oxidized samples were characterized by using X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), and scratch tester to obtain the oxide phases, morphology, thickness, composition and adhesion property of the oxide scales. The experiment results indicated that a small amount of Ce addition (0.02 wt.% or 0.05 wt.%) promoted oxidation resistance and inhibited the growth of the needlelike oxide. The Ce addition also decreased the formation of MnCr2O4 but promoted the SiO2 formation un-derneath the Cr2O3, which largely contributed to the improvement of oxide scale spallation resistance. For the sample with 0.3 wt.% Ce addi-tion, the oxidation rate significantly increased and the spallation resistance of the oxide scale decreased.