Powder Metallurgical Processing of Ti6Al4V Alloy

Ti6Al4V powders were produced by Argon gas atomization, the powder fraction ＜ 250μm was hot isostatically pressed (HIP) at 920°C and 140MPa. The properties of pre-alloyed powders and the compact were investigated in this paper. Powder particles are almost perfectly spherical. The microstructure of powder surface is approximate hexagonal cellular structure, the inner structure exhibits cellular αphase and needle-like martensiteα′ phase, these are resulting from the rapid solidification. After HIP, Ti6Al4V alloy has a Widmanstaten microstructure consisting of continuous grain boundary α（GBα）phase and β transformation structure, the grain size of GBα phase is in the range of 5～15μm . The tensile test at room temperature shows that strength of samples is 880MPa, the fracture surface exhibits obvious brittle cleavage fracture features including cleavage facets with river pattern and a few elongate dimples of different sizes and big voids at localized area.

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Effects of cyclic thermo-hydrogen processing on microstructural and mechanical properties of Ti6Al4V alloy at room temperature

Vacuum ◽

10.1016/j.vacuum.2019.109015 ◽

2020 ◽

Vol 171 ◽

pp. 109015 ◽

Cited By ~ 6

Author(s):

Baoguo Yuan ◽

Xiaoxue Zhang ◽

Yujie Wang ◽

Qiang Chen ◽

Yuanyuan Wan ◽

...

Keyword(s):

Mechanical Properties ◽

Room Temperature ◽

Ti6al4v Alloy

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Fractography of Reaction-Sintered Si3N4

Journal of Engineering for Power ◽

10.1115/1.3230244 ◽

1980 ◽

Vol 102 (2) ◽

pp. 244-248

Author(s):

M. G. Mendiratta ◽

P. L. Land ◽

R. Ruh ◽

R. W. Rice ◽

D. C. Larsen

Keyword(s):

High Temperatures ◽

Fracture Mode ◽

Room Temperature ◽

Size Range ◽

Fracture Initiation ◽

Transgranular Fracture ◽

Four Point Bending ◽

Fracture Appearance ◽

Fracture Features

Fractography studies were accomplished on two reaction-sintered Si3N4 materials (Norton NC-350 Si3N4 and KBI (Kawecki-Berylco) Si3N4) which had been tested in four-point bending at room temperature, 1200, 1350, and 1500°C in air. At room temperature NC-350 exhibited uniform planar features representing a transgranular fracture mode, uniformly distributed small pores having a size range of 1–2 μm or less, and a few isolated large pores of ∼10 μm. In contrast, the KBI Si3N4 at room temperature exhibited nonuniform, diffuse, and ill-defined fracture features, small pores having a size range of 2–5 μm, and many large pores of ∼50 μm in size. At high temperatures, the fracture appearance of NC-350 Si3N4 was ill defined and diffuse, indicating a change in fracture mode. The fracture originating flaws in NC-350 were primarily the large pores or pore agglomerates. At all temperatures, in the KBI material, it was not possible to observe the mirror and, therefore, the site of fracture initiation. For NC-350, KIC values were 1.2–1.6 MN/m3/2 at room temperature and 2.1–2.4 MN/m3/2 at high temperatures.

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Features of Amorphization of the Fe-TM-Nd-REM-B Alloys System at Melt Quenching by Gas Atomization

Journal of Metastable and Nanocrystalline Materials ◽

10.4028/www.scientific.net/jmnm.31.51 ◽

2019 ◽

Vol 31 ◽

pp. 51-55

Author(s):

Mikhail Sorokovikov ◽

Valeriy V. Savin ◽

Ludmila A. Savina ◽

V.A. Chaika ◽

I.S. Zherebcov

Keyword(s):

Chemical Composition ◽

Cooling Rate ◽

Primary Crystallization ◽

Primary Phase ◽

Gas Atomization ◽

Spherical Powder ◽

Similar Chemical ◽

Powder Particles ◽

The Moment ◽

Triple Eutectic

Gas atomization powders (GAP) chemical composition which corresponds to the first area of the phase equilibrium, and the fraction that ensures a cooling rate of a separate powder particle of more than 103K/s contains an amorphous component of two types: the first (AC1) has a chemical composition similar to that of the alloy; and the second (AC2) has a chemical composition of the triple eutectic. AC1 is mostly localized on the surface of the powder particles (in the form of layers, shells, nodules) or are detected in the whole volume of the spherical powder particles with its size less than 5 μm. The authors hold that during gas atomization, powder particles of this size have a cooling rate ≥ 105 K/s. Alloys having a similar chemical composition at similar cooling rates are also amorphized by quenching from the liquid state. This proves that an amorphous alloy of the first type is formed directly from a supercooled melt. While AC2 (enriched by Nd) is formed on the border or in the between the crystal phase Fe14Nd2B of the remaining (after primary crystallization during the primary phase) melt enriched by the moment of the solidification of Nd.

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Discharge Enhancement Effect of Inorganic Nanometer Spark Plasma Sintering Aid

Materials Science Forum ◽

10.4028/www.scientific.net/msf.850.829 ◽

2016 ◽

Vol 850 ◽

pp. 829-834

Author(s):

Hao Feng Li ◽

Ming Gang Wang ◽

Zhan Kui Zhao

Keyword(s):

Spark Plasma Sintering ◽

Sintering Temperature ◽

Physical Method ◽

Silicon Steel ◽

Enhancement Effect ◽

Gas Atomization ◽

Sintering Aid ◽

Plasma Sintering ◽

Spark Plasma ◽

Powder Particles

CaF2 inorganic nanometer powder particles were used as sintering aid to sintering good conductive Fe-6.5Si alloy. By a physical method, CaF2 inorganic nanopowder particles were made with a granularity of 15-30 nm assembled between micron-sized Fe-6.5Si powder particles prepared by gas atomization. 6.5 % Si high silicon steel were fabricated by spark plasma sintering (SPS) with varying contents of CaF2. The discharge enhancement effect of CaF2 inorganic nanospark plasma aid is confirmed. The initial sintering temperature and the final sintering temperature were decreased by 75 °C and 70 °C respectively with 0.5 % CaF2 inorganic nanopowder aid. In the case of reduced 60 °C, the higher density for the particles with the addition of CaF2 was observed compared with without CaF2. When the nanopowder was 2%, sintering performance decreased. The study indicates that sintering pressure has an enormous effect on the Fe-6.5Si sintering effect.

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Ambient Temperature Synthesis of Bulk Intermetallics

MRS Proceedings ◽

10.1557/proc-350-41 ◽

1994 ◽

Vol 350 ◽

Author(s):

M. Ratzker ◽

D. S. Lashmore ◽

M. P. Dariel

Keyword(s):

Ambient Temperature ◽

Room Temperature ◽

Binary Systems ◽

Electronic Materials ◽

Close Contact ◽

Interface Area ◽

Compound Formation ◽

Intermetallic Compound Formation ◽

Powder Particles ◽

Size Powder

AbstractRoom-temperature intermetallic compound formation occurs when one of the component metals has a very low melting point or when two metals in close contact interdiffuse very rapidly. Compound formation at room temperature at the interface of superposed thin films has been observed in several instances, often in systems relating to electronic materials. The overall amount of compound produced in such configurations, however, is limited, due to the intrinsic limitations involved in the thin layer geometry. Bulk quantities of intermetallic can be produced at ambient temperature in solids by increasing the interface area between the components that interdiffuse rapidly. This condition can be achieved by having small size powder particles of one component coated with a layer of the second component. The very large interface area leads to rapid formation of bulk quantities of compounds even at ambient temperature. By appropriate control of the initial constituents and the coating parameters, it is possible to custom-prepare various intennetallic compounds present in binary systems such as silver-tin, gold-tin and silver-indium in which fast interdiffusion takes place.

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Friction/Wear Behaviors of Magnetron Sputtered TiB2-C Composite Films on Ti6Al4V Alloy Substrate

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.189-193.979 ◽

2011 ◽

Vol 189-193 ◽

pp. 979-982

Author(s):

Xiao Jing Xu ◽

Xin Lan Sheng ◽

Dan Chen ◽

Xi Ling Xin ◽

Kun Tian ◽

...

Keyword(s):

Room Temperature ◽

Composite Films ◽

Ti6al4v Alloy ◽

Wear Properties ◽

Microstructural Characteristics ◽

Carbon Doped ◽

Alloy Substrate ◽

Sic Films ◽

Ball On Disc

The microstructure and friction/wear properties of TiB2-C (carbon-doped TiB2) films in TiB2-C/SiC double layer films (SiC films as interlayer) deposited on Ti6Al4V alloy substrate using magnetron sputtering technique at room temperature were investigated. The results show that the TiB2-C films exhibited the microstructural characteristics with nano-scale particles (domains), and the doped-carbon presented in manner of sp3 C-C and sp2 C-C bonds i.e. DLC (diamond-like carbon). The interface between the substrate and the SiC films and the interface between the SiC films and the TiB2-C composite films both showed good adhesion, with obvious element diffusions. As sliding against Si3N4 (silicon nitride) balls (2 mm in radius) using ball-on-disc type wear tester at room temperature under Kokubo simulation body fluid (SBF) and 50g load, the TiB2 -C composite films exhibited the friction coefficient of about 0.14 and the specific wear rate of 10.710-6 mm3 m−1 N−1. It is believed that the superior friction properties of the TiB2-C films are due to the role of the doped-carbon.

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Processing and Properties of FeAl Sheets Obtained by Roll Compaction and Sintering of Water Atomized Powder

MRS Proceedings ◽

10.1557/proc-552-kk4.6.1 ◽

1998 ◽

Vol 552 ◽

Cited By ~ 4

Author(s):

S. C. Deevi ◽

M. R. Hajaligol ◽

V. K. Sikka ◽

J. McKernon ◽

C. R. Scorey

Keyword(s):

Room Temperature ◽

Annealing Temperature ◽

Vacuum Annealing ◽

Reduction Process ◽

Vacuum Furnace ◽

Al Content ◽

Metallurgical Processing ◽

Fine Microstructure ◽

Roll Compaction ◽

Edge Cracking

ABSTRACTThe low ductilities of FeAl alloys led us to explore powder metallurgical processing technology to obtain sheets of 0.2mm thickness as opposed to manufacturing processes based on hot rolling of cast FeAl alloys. In our approach, water atomized FeAl powders were roll compacted to 0.66mm with a polymeric binder using two counter rotating rolls to a green density of 3.1 g/cc. Roll compacted green sheets were then de-bindered in nitrogen in the temperature range of 300 to 600°C for several hours prior to sintering the sheets in vacuum. Sintered sheets were rolled down from 0.66 to 0.20 mm in three different stages resulting in a total reduction of 69% Vacuum annealing of the sheets was carried out between each stage of the reduction process to eliminate edge cracking associated with the work hardening of the FeAl. The properties of the FeAl sheets depend on the Al content, annealing temperature and time in a vacuum furnace. The fine microstructure of FeAl sheets led to tensile elongations of 4 to 6%. The sheets are formable at room temperature, and possess excellent mechanical properties both at room and high temperatures.

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Formation of nanocrystalline B2-structured (Fe,Ni)Al in mechanically alloyed Fe50Al30Ni20 (wt.%) powder

New Trends and Issues Proceedings on Advances Pure and Applied Sciences ◽

10.18844/gjapas.v0i9.3018 ◽

2018 ◽

pp. 66

Author(s):

Nakib Chafika

Keyword(s):

Dislocation Density ◽

Mechanical Alloying ◽

Room Temperature ◽

X Ray Diffraction ◽

Mechanically Alloyed ◽

Sem Images ◽

X Ray ◽

Paramagnetic Behaviour ◽

Powder Particles ◽

Bcc Phase

B2-structured (Fe,Ni)Al was synthesised by an abrupt reaction during mechanical alloying (MA) of the elemental powders of Fe, Al and Ni. The structural, microstructural, morphological and magnetic changes occurring in the studied material during MA were investigated by X-ray diffraction (XRD) and scanning electron microscopy (SEM). Two crystalline phases were found, a majority one corresponding to (Fe,Ni)Al bcc phase with a crystallite size less than 10 nm, a lattice strain up to 1.6% and a dislocation density of about 2.3 x1016 m-2. The other phase was in a low proportion corresponding to Fe (Al,Ni) solid solution. SEM images showed an irregular morphology of powder particles. Mossbauer spectra of the milled powders, recorded at room temperature, reveal the paramagnetic behaviour of the obtained powder. Keywords: Mechanical alloying, ternary composition, dislocation density, structural properties, paramagnetic behaviour.

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