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RISS 인기검색어
- 검색키워드
- 저자 : Suryanarayana C. (검색결과 8 건)
- 무료
- 기관 내 무료
- 유료
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Nanocrystalline Materials-an Overview
Suryanarayana, C. The Korean Powder Metallurgy Institute 1996 한국분말재료학회지 (KPMI) Vol.3 No.4
Nanocrystalline materials, with a grain size of typically <100 nm, are a new class of materials with properties vastly different from and often superior to those of the conventional coarse-grained materials. These materials can be synthesized by a number of different techniques and the grain size, morphology, and composition can be controlled by controlling the process parameters. In comparison to the coarse-grained materials, nanocrystalline materials show higher strength and hardness, enhanced diffusivity, improved ductility/toughness, reduced, density, reduced elastic modulus, higher electrical resistivity, increased specific heat, higher coefficient of thermal expansion, lower thermal conductivity, and superior soft and hard magnetic properties. Limited quantities of these materials are presently produced and marketed in the US, Canada, and elsewhere. Applications for these materials are being actively explored. The present article discusses the synthesis, structure, thermal stability, properties, and potential application of nanocrystalline materials.
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Recent Advances in the Synthesis of Alloy Phases by Mechanical Alloying/Milling
SURYANARAYANA, C 대한금속재료학회(대한금속학회) 1996 METALS AND MATERIALS International Vol.2 No.4
Mechanical alloying (MA) is a solid-state powder processing technique involving repeated welding, fracturing, and rewelding of powder particles in a high-energy ball mill. Originally developed to produce oxidedispersion strengthened nickel- and iron-base superalloys, MA has now been shown to be capable of synthesizing a number of alloy phases - equilibrium and supersaturated solid solutions, stable and metastable crystalline and quasicrystalline intermediate phases, and amorphous alloys. Recent advances in these areas and also on disordering of ordered intermetallics and displacement reactions have been critically reviewed. Wherever possible, comparisons have been made on the product phases obtained by MA and by rapid solidification processing, another non-equilibrium processing technique.
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Consolidation of Nanocrystalline Powders
Suryanarayana, C .,Korth, G . E . 대한금속재료학회(대한금속학회) 1999 METALS AND MATERIALS International Vol.5 No.2
Blended elemental Ti-24Al-11Nb (at.%) and Ti-SSA1 (at.%) powders were mechanically alloyed and consolidated to full density by hot isostatic pressing (HlPing), Ceracon processing, and shock consolidation methods. Nanometer-sized grains were observed in all the samples, the finest size achieved in the shock-consolidated samples. The grain size was larger at higher HIPing temperatures. In comparison with conventional coarse-grained material, the HIP temperature for full consolidation could be brought down by about 400℃ for the nanostructured titanium aluminides.
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Nanostructured Materials and Nanocomposites by Mechanical Alloying: An Overview
C. Suryanarayana,Ahmed A. Al‑Joubori,Zhi Wang 대한금속·재료학회 2022 METALS AND MATERIALS International Vol.28 No.1
The technique of mechanical alloying, although originally developed to produce oxide-dispersion-strengthened superalloysfor aerospace and high-temperature applications, is now recognized as an important and versatile technique to synthesizemetastable and advanced materials with a high potential for widespread applications. Mechanical alloying involves repeatedcold welding, fracturing, and rewelding of powder particles in a high-energy ball mill. The reduced difusion distancesbetween metal powder layers formed as a result of heavy deformation, introduction of a high density of crystal defects, and aslight rise in powder temperature contribute to alloy formation from blended elemental powders. The type of phases/materialsproduced by mechanical alloying of powder mixtures include supersaturated solid solutions, intermetallics, quasicrystallinealloys, high-entropy alloys, amorphous alloys, and composites. If the material produced is crystalline in nature, most oftenthe grain size is in the nanometer size. Amongst these phases, nanostructured materials and nanocomposites have been themost important types investigated. In this contribution, we will present an overview of the processing, characteristics, andproperties of nanocrystalline materials and nanocomposites produced by mechanical alloying, with special emphasis on ourrecent work.
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THE SCIENCE AND TECHNOLOGY OF MECHANICAL ALLOYING
Suryanarayana C. 한국분말야금학회 2000 한국분말야금학회 학술대회논문집 Vol.2000 No.1
Mechanical alloying (MA) is a powder metallurgy processing technique involving cold welding fracturing and rewelding of powder particles in a high-energy ball mill. This has now become an established commercial technique in producing oxide dispersion strengthened (ODS) nickel- and iron-based materials. The technique of MA is also capable of synthesizing non-equilibrium phases such as supersaturated solid solutions metastable crystalline and quasicrystalline intermetallic phases nanostructures and amorphous alloys. In this respect the capabilities of MA are similar to those of another important non-equilibrium processing technique viz rapid quenching of metallic melts. however the science of MA is being investigated only during the past ten years or so. The technique of mechanochemistry on the other hand has had a long history and the materials produced this way have found a number of technological applications e.g. in areas such as hydrogen storage materials heaters gas absorber fertilizers. catalysts cosmetics and waste management. The present talk will concentrate on the basic mechanisms of formation of non-equilibrium phases by the technique of MA and these aspects will be compared with those of rapid quenching of metallic melts. Additionally the variety of technological applications of mechanically alloyed products will be highlighted.
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Microstructure and mechanical properties of Al-Zr nanocomposite materials
Srinivasarao, B.,Suryanarayana, C.,Oh-ishi, K.,Hono, K. Elsevier Sequoia 2009 Materials science & engineering. properties, micro Vol.518 No.1
Three different processing routes were explored to develop Al-Zr nanocomposite alloys using mechanical alloying and spark plasma sintering methods. Depending on the route of milling adopted, the powder in the as-milled condition consisted of either a solid solution of Zr in Al or a mixture of Al-solid solution and Al<SUB>3</SUB>Zr (L1<SUB>2</SUB>) phases. The alloys after sintering consisted of Al and Al<SUB>3</SUB>Zr (L1<SUB>2</SUB>) with grain sizes of less than 100nm. These nanocomposite alloys exhibited a high compressive strength of 1GPa with 10% plasticity. The high strength observed in these alloys was explained on the basis of the retention of nanometer sized grains and also the fine dispersion of the L1<SUB>2</SUB> phase. On the other hand, the good amount of plasticity was explained to be due to excellent bonding between the powder particles and the presence of coarse Al grains in the matrix.
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Hot Isostatic Pressing of Nanostructured γ - TiAl Powders
HEBEISEN, J,TYLUS, P,ZICK, D,MUKHOPADHYAY, D K,BRAND, K,SURYANARAYANA. C,FROES. F H 대한금속재료학회(대한금속학회) 1996 METALS AND MATERIALS International Vol.2 No.2
A study of the hot isostatic pressing (HIP'ing) of γ-TiAl powders produced by mechanical alloying, has demonstrated that full density can be achieved 400℃ or more below the temperature required for conventional powder; that is 725℃ or below. Nanostructured grains (≤100 ㎚) are observed after HIP'ing up to 850℃.
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