共查询到20条相似文献,搜索用时 31 毫秒
1.
G. M. Janowski F. S. Biancaniello S. D. Ridder 《Metallurgical and Materials Transactions A》1992,23(12):3263-3272
Fully dense nitrogenated austenitic stainless steels were produced by gas atomization and HIP consolidation. The base alloy,
304L, contained about 0.15 wt pct nitrogen when melted under a nitrogen atmosphere, and a modified version of 304L with 23
wt pct Cr contained 0.21 wt pct nitrogen. A series of experiments using various combinations of N2 and Ar as the melt chamber backfill gas and atomizing gas demonstrated that the nitrogen content of the powder was largely
controlled by the backfill gas and that the fraction of hollow particles was determined by the atomization gas. The hollow
powder particles, which are common in inert-gas atomized materials, were virtually eliminated in the nitrogen atomized powders.
Additional atomizing experiments using copper and a nickel-base superalloy indicate that low gas solubility in the metal leads
to gas entrapment. Hardness and compression behavior (yield strength and flow stress) are substantially improved with the
addition of nitrogen. The results of this study suggest that the properties of nitrogenated stainless steels fabricated in
this manner are comparable to other high nitrogen austenitic alloys.
G.M. JANOWSKI, formerly NRC/NIST Postdoctoral Research Associate, National Institute of Standards and Technology. 相似文献
2.
3.
采用水雾化法制备铁锰无磁合金粉末, 分析了合金粉末含锰质量分数和雾化工艺对铁锰合金粉末性能的影响规律。结果表明: 水雾化法生产铁锰无磁合金粉的方案可行, 但锰质量分数不宜低于24%;在实验工况条件下, 雾化压力对松装密度的影响可以忽略不计, 雾化压力提高使产品流动性变差, 以15 MPa雾化压力进行生产时, 产品工艺性能(松装密度、流动性) 最好; 雾化压力的提高有助于提高产品烧结密度, 在满足产品流动性要求的前提下, 可以考虑通过提高雾化压力来提高产品烧结密度。 相似文献
4.
利用正交试验研究了电极感应气雾化(electrode induction gas atomization,EIGA)制粉工艺参数(雾化压力、雾化气体温度和熔炼功率)对新型高硬度马氏体铁基合金粉末粒径分布、粉末流动性和收得率的影响规律。结果表明,粉末粒径分布及其特征主要取决于雾化压力,粉末流动性及收得率主要受雾化压力及雾化气体温度的影响。当制粉工艺参数为雾化压力1.5 MPa、熔炼功率15 kW、雾化气体温度40 ℃时,所得粉末的收得率最高,粒径大小在53~180 μm之间的粉末质量占比高达68.24%,兼具较好的粉末流动性及粉末粒度分布标准偏差,粉末形貌最佳。 相似文献
5.
以TiAl合金块为原料,利用水冷铜坩埚真空感应熔炼气雾化技术制粉,通过对导流系统和雾化器的优化改进,制备出氧含量低、细粉收率高的球形TiAl合金粉末。结果表明,将导热性好的石墨导流基座和耐冲刷的BN材质陶瓷导流内芯配合使用,既可以保证导流管加热,也可以有效阻止金属熔液的冲刷;螺旋喷管雾化器使雾化点下移,回流区位置远离导流管出口,解决了液柱反流的问题。螺旋分布管能够有效约束雾化气体,动能损失小,能够显著提高细粉收率达20%以上。实验制备的球形TiAl合金粉末流动性为27.7 [s·(50 g)?1],球形度>90%,粉末氧增量小,适用于3D打印和注射成型工艺用粉。 相似文献
6.
7.
金属熔体气体雾化法是制备增材制造专用金属粉末的重要方法。然而,气体雾化工艺制得的粉末中通常混有大量卫星粉,对金属增材制造工艺产生不利影响。本文通过施加辅助气流并采用阶梯状雾化室结构等气体整流措施抑制回流区中的粉尘回旋,进而控制卫星粉的形成。利用计算流体力学软件ANSYS Fluent进行数值模拟,研究施加辅助气流或采用阶梯状雾化室结构时,雾化室内宏观流场特征以及颗粒运动轨迹的变化规律。结果表明,在雾化室顶部距雾化室中心R/2(R为雾化室半径)处施加辅雾比(辅助气流与雾化气流的流量比)大于0.8的辅助气流时能够有效抑制回流区中的粉尘回旋;采用阶梯宽为300 mm、高为575~600 mm的雾化室结构能够有效抑制回流区中的粉尘回旋。根据数值模拟结果,采用气体整流措施制备TC4钛合金粉末,并检测粉末的粒径分布、球形度、赘生物指数等指标,发现与不采用气体整流措施制备的粉末相比,赘生物指数降低约45%。 相似文献
8.
开展了采用紧耦合气雾化方法制备Al基合金粉末的实验和理论研究.利用X射线衍射仪、差热分析仪、扫描电镜和透射电镜分析了粉末的表面形貌、显微组织和结构特征,根据气雾化过程中熔滴的破碎模式和冷却行为确定了Al基合金的非晶化临界冷却速率及相应粉末粒径.结果表明:气雾化粉末中存在部分非晶粉末,非晶粉末的粒径小于26μm;Al基合金的非晶化临界冷却速率大致为106K·s-1;雾化中熔体的破碎和冷却是两个相互耦合(矛盾)的过程,快速冷却(大于104K·s-1)极大地阻碍熔体的充分雾化,同时熔滴的破碎模式对其冷却行为具有显著的影响.目前紧耦合气雾化技术还只能制得非晶/晶态混合的Al基合金粉末. 相似文献
9.
10.
对液体稀土硅铁的粘度和表面张力进行了测定和分析;还对稀土硅铁的各种雾化工艺进行了实验研究,找出一种新的制粉工艺,采用“氩吹一空冷”联合流程,制得了适合喷射冶金需要的粒度范围在0.2mm~2.0mm、流动性能良好的稀土硅铁粉末。同时还对稀土硅铁制粉过程应用高速摄影技术进行了分析,对雾化制粉的机理进行研究。 相似文献
11.
T. W. Ellis I. E. Anderson H. L. Downing J. D. Verhoeven 《Metallurgical and Materials Transactions A》1993,24(1):21-26
Wires have been fabricated by deformation processing of precursor billets that were prepared from alloy powders made by high-pressure
gas atomization (HPGA) of a copper-20 vol pct niobium melt. The powders were classified, and a larger size fraction, whose
microstructure consisted mainly of 0.4-μm-diameter Nb dendrites, was fabricated into the precursor billet by powder metallurgical techniques. The deformation-processed
wire prepared from the powder alloy billet gave significantly increased strengths at a given level of deformation strain over
similar material produced by consumable arc casting. This may be attributed to the smaller initial Nb dendrite size of the
alloy powder used for the precursor billet. However, the electrical conductivity of the powder material at a given strength
level was significantly lower than the arccast material. The cause of the reduction of the conductivity is uncertain, and
possible reasons are discussed.
This article is based on a presentation made in the symposium “High Performance Copper-Base Materials” as part of the 1991
TMS Annual Meeting, February 17–21, 1991, New Orleans, LA, under the auspices of the TMS Structural Materials Committee. 相似文献
12.
A. A. Ezhov V. I. Shvarts L. M. Bernshtein O. Ya. Beilina I. Ya. Kondratov A. F. Palamarchuk V. T. Zubkova A. F. Klimenko 《Powder Metallurgy and Metal Ceramics》1980,19(9):643-646
Conclusions An investigation into the structure and morphology of a 30KhN3MF steel powder produced by atomizing a jet of liquid metal with nitrogen has shown that the rapid cooling experienced by the particles of such a powder ensures a predominantly cellular character of solidification. In the particles of the 30KhN3MF steel powder intercellular microsegregation of alloying and impurity elements is observed. A P/M material produced by HIP is free from internal discontinuities, but individual granules surrounded by oxide films are clearly visible in its macro- and microstructures. The presence of these films, by disturbing the homogeneity of material, has an adverse effect on the mechanical properties of the steel after HIP. P/M 30KhN3MF steel fractures over the surfaces of its powder particles. Plastic working and subsequent heat treatment of 30KhN3MF steel sheets ensures that, at the same level of toughness and strength and ductility characteristics in static tensile testing, the work of crack propagation is greater compared with 30KhN3MF steel produced by the orthodox process. The rupture of 30KhN3MF steel sheet has a dual character, tough, fine-grained fracture predominating between the oxide film layers, along which regions of lamination and cleavage can be detected.A low-alloy 0.30% C-Cr-3% Ni-Mo-V grade-Translator.Translated from Poroshkovaya Metallurgiya, No. 9(213), pp. 77–82, September, 1980. 相似文献
13.
球形粉末是增材制造、粉末冶金、注射成型等制备工艺的重要原料,其成分、粒度、球形度、空心粉率等是影响最终构件性能的关键因素。本文详细介绍了真空感应熔炼气雾化法、电极感应熔炼气雾化法以及等离子旋转电极雾化法等三种可用于增材制造的工程化高温合金球形粉末的制备技术,分析了这三种制粉工艺的特点,阐述了这三种制粉工艺的研发进展,探讨了三种制粉工艺所制备的粉末缺陷形成原因及控制方法,并提出了增材制造用高温合金粉末制备技术的发展趋势。 相似文献
14.
Fe-Ni-Mo-Cu-Co-Cr-Mn水雾化合金钢粉的研制 总被引:1,自引:0,他引:1
本文介绍了一种用于生产汽车排气阀座的Fe Ni Mo Cu Co Cr Mn水雾化合金钢粉的研制过程 ,分析了有关工艺控制对该种含Cr、Mn易氧化元素粉末氧含量和颗粒形状、粒度组成、松装密度、压缩性、流动性等性能指标的影响 ,确定了为获得低碳、低氧含量、高松装密度、高压缩性和高成形性的Fe Ni Mo Cu Co Cr Mn水雾化合金钢粉应采取的有关措施 ,为批量生产质优价廉的排气阀座用水雾化合金钢粉找出了一条有效的途径。 相似文献
15.
Ashish Agrawal Ravindra Kumar Dube 《Transactions of the Indian Institute of Metals》2018,71(10):2541-2552
The present work describes a new route for the preparation of Cu–Al–Ni alloy strips via spray atomization and deposition route. The route consists of atomizing liquid Cu–Al–Ni alloy with a jet of argon gas in a closed chamber, at a pressure of 1 MPa. The semi-solid Cu–Al–Ni droplets are subsequently collected on the steel substrate placed vertically below the liquid metal stream in the atomization chamber to form a three-dimensional preform. The deposit produced on the substrate contains ~?5% porosity. The microstructural details of the spray deposited Cu–Al–Ni strips explains particularly the presence of porosity, formation of splats during the flight of spray casting and the associated microstructural evolution in Cu–Al–Ni spray deposit are explained. 相似文献
16.
A. Inoue T. Masumoto T. Ekimoto S. Furukawa Y. Kuroda H. S. Chen 《Metallurgical and Materials Transactions A》1988,19(2):235-242
By using newly constructed high-pressure gas atomization equipment, the effect of atomizing gas (Ar, N2, or He) on the formation tendency of amorphous alloy powders and their Curie temperature(T
c
), structural relaxation, glass transition(T
g
), and crystallization(T
x
) was examined for Fe-P-C, Fe-Si-B, Fe-Cr-Mo-P-C, Co-Si-B, Ni-Si-B, Ni-Pd-P, and Cu-Zr alloys with easy glass-forming capacity.
Amorphous powders are formed in all the alloy systems and the critical diameter for the formation of amorphous powders is
25 to 44 μm for Ar and 44 to 100 μm for He. The average particle size is considerably smaller for He than for Ar and N2, probably because of large kinematic viscosity of He. No appreciable differences inT
c
,T
g
, andT
x
of Fe77P13C10 amorphous powders with the kind of atomizing gas are seen and these values are the same as those of the amorphous ribbon
with 20 μm thickness. However, He-atomized Fe77P13C10 powders exhibit a lower onset temperature of relaxation and larger heats of relaxation and crystallization as compared with
the Ar- and N2-atomized powders, and the values of the He-atomized powders are comparable to those of the ribbon sample, indicating that
He-gas atomization has a higher cooling capacity and results in the formation of a more disordered amorphous structure. This
difference agrees with the tendency estimated under the assumption that heat removal from atomized droplets occurs by Newtonian
cooling caused only by the convective heat transfer. Accordingly, the greater heat removal capacity of He gas is concluded
to be a dominant factor for the formation of amorphous alloy powders with a more unrelaxed atomic configurations. 相似文献
17.
B. N. Putimtsev 《Powder Metallurgy and Metal Ceramics》1968,7(11):839-844
Conclusions The results are presented of an investigation into the influence of melting technique, melt composition, and the atomizing medium on the fabricating and physical properties of powders with spherical, compact particles. Characteristic features of the disintegration of metallic melts and of the shaping and oxidation of particles in the air and nitrogen atomization of the melt stream are examined. The desirability is demonstrated of deoxidizing metals and alloys by diffusion in the melting process and employing inert atomizing media to obtain oxide free powders of ferromagnetic metals and alloys. On the basis of this investigation, recommendations are given for the production of high quality ferromagnetic powders for use in electrical apparatus.Translated from Poroshkovaya Metallurgiya, No. 11(71),pp. 1–7, November, 1968. 相似文献
18.
以真空自耗电弧熔炼的Ti-35.8Al-18.4Nb(质量分数)合金铸锭为原料,采用水冷铜坩埚真空感应熔炼气雾化制粉技术(water-cooled copper crucible vacuum induction melting-gas atomizing,VIGA-CC)制备球形Ti-35.8Al-18.4Nb合金粉末,利用振动筛分法、扫描电子显微镜(scanning electron microscope,SEM)观察、X射线衍射(X-ray diffraction,XRD)分析等手段对所制备的粉末进行性能表征。结果表明,VIGA-CC技术制备的粉末粒度分布较宽,主要分布在45~150 μm之间,呈正态分布,其中粒径不高于45 μm粉末收得率为15.8%,粒径不低于150 μm粉末收得率为12%;粉末流动性为27.2[s·(50 g)-1],粉末中氧质量分数的增量小于0.01×10-6,粉末整体氧质量分数小于0.06×10-6;TiAlNb合金粉末主要以γ(TiAl)相和α2(Ti3Al)相为主,随着粉末粒径的减小,冷却速率逐渐提高,γ(TiAl)相逐渐减少,α2(Ti3Al)相逐渐增加;大颗粒粉末表面为枝状冷凝组织,小颗粒粉末为光滑表面。 相似文献
19.
《Acta Metallurgica Materialia》1994,42(4):1351-1358
The shape memory properties of the TiNi alloy produced by a powder metallurgical method have been evaluated from tensile stress-strain curves. The contamination of the powders during atomization can be suppressed by applying the Plasma Rotating Electrode Process (P-REP), so that the compact made by Hot Isostatic Pressing (HIP) is expected to exhibit the shape memory effect identical to the typical alloy grown from melt. The fracture behavior of the P/M alloy is also studied, and the improvement of fracture strength of the P/M alloy is attempted. 相似文献
20.
Microstructural features and heat flow analysis of atomized and spray-formed Al-Fe-V-Si alloy 总被引:5,自引:0,他引:5
A. K. Srivastava S. N. Ojha S. Ranganathan 《Metallurgical and Materials Transactions A》1998,29(8):2205-2219
Microstructural features of rapidly solidified powders and preforms of Al80Fe10V4Si6 alloy produced by spray forming process have been studied. The atomization and spray deposition were carried out using a
confined gas atomization process and the microstructural features were characterized using scanning electron microscopy and
transmission electron microscopy (TEM) and X-ray diffraction (XRD) techniques. The microstructure of a wide size range of
atomized powders invariably revealed cellular and dendritic morphology. The extent of dendritic region and the dendritic arm
spacing were observed to increase with powder particle size. The TEM investigations indicated the presence of ultrafine second-phase
particles in the intercellular or interdendritic regions. In contrast, the spray deposits of the alloy showed considerable
variation in microstructure and size and dispersion of the second-phase particles at specific distances from the deposit-substrate
interface and the exterior regions of the deposit. Nevertheless, considerable homogeneity was observed in the microstructure
toward the center of the spray deposit. The formation and distribution of a cubic phase α-Al(Fe,V)Si has been characterized in both atomized powders and spray deposits. A one-dimensional heat flow model has been
used to analyze the evolution of microstructure during atomization and also during spray deposition processing of this alloy.
The results indicate that thermal history of droplets in the spray on deposition surface and their solidification behavior
considerably influence the micro-structural features of the spray deposits. 相似文献