Structural Evaluation of Mechanically Alloyed and Heat-Treated Ti-25at-%Si Powders

2012 ◽  
Vol 727-728 ◽  
pp. 227-232
Author(s):  
Marisa Aparecida de Souza ◽  
Erika Coaglia Trindade Ramos ◽  
Alfeu Saraiva Ramos
Keyword(s):  
Energy Dispersive Spectrometry ◽  
Weight Ratio ◽  
Amorphous Structure ◽  
Milling Process ◽  
X Ray Diffraction ◽  
Mechanically Alloyed ◽  
Scanning Calorimetry ◽  
Structural Evaluation ◽  
Heat Treated ◽  
Steel Balls

This work discusses on the structural evaluation of mechanically alloyed and heat-treated Ti-25at%Si powders. The milling process was conducted in a planetary ball mill using stainless steel balls/vials, 200 rpm and ball-to-powder weight ratio of 5:1, whereas the heat treatment was conducted under Ar atmosphere at 1100°C for 4 h. Samples were characterized by X-ray diffraction, differential scanning calorimetry, scanning electron microscopy and energy dispersive spectrometry. The Si peaks disappeared after milling for 30h, indicating that the Si atoms were dissolved into the Ti lattice in order to form an extended solid solution. The Ti peaks were broadened and their intensities reduced for longer milling times whereas a halo was formed in Ti-25Si powders milled for 200h suggesting that an amorphous structure was achieved. The crystallite size was decreased with increasing milling times. A large Ti3Si amount was found in mechanically alloyed Ti-25at%Si powders after heating at 1100°C for 4h.

High-Energy Ball Milling and Sintering of Ti-2Ta-22Si-11B and Ti-6Ta-22Si-11B Powders Mixtures

2014 ◽  
Vol 802 ◽  
pp. 20-24 ◽  
Author(s):  
Lucas Moreira Ferreira ◽  
Luciano Braga Alkmin ◽  
Érika C.T. Ramos ◽  
Carlos Angelo Nunes ◽  
Alfeu Saraiva Ramos
Keyword(s):  
Ball Milling ◽  
Weight Ratio ◽  
High Energy ◽  
Milling Process ◽  
Wet Milling ◽  
X Ray Diffraction ◽  
Heat Treated ◽  
Equilibrium Structures ◽  
Rotary Speed ◽  
Steel Balls

The milling process of elemental Ti-2Ta-22Si-11B and Ti-6Ta-22Si-11B (at-%) powder mixtures were performed in a planetary Fritsch P-5 ball mill using stainless steel vials (225 mL) and hardened steel balls (19 mm diameter). Ball-to-powder weight ratio of 10:1 and a rotary speed of 300 rpm were adopted, varying the milling time. Wet milling (isopropyl alcohol) for 20 more minutes was used to increase the yield powder in to the vial. Following the Ti-Ta-Si-B powders milled for 600 min were heat-treated at 1100°C for 1 h in order to obtain the equilibrium structures. The milled powders and heat-treated samples were characterized by X-ray diffraction, scanning electron microscopy, and energy dispersive spectrometry. Supersaturated Ti solid solutions were formed during ball milling of Ti-Ta-Si-B powders while that the Ti5Si3 phase was formed after milling for 620 min of the Ta-richer powder mixture only. The particles sizes were initially increased during the initial milling times, and the wet milling provided the yield powder into the vials. A large amount of pores was found in both the sintered samples which presented the formation of the TiSS,(ss-solid solution) Ti6Si2B and TiB.

Structural Evaluation of Mechanically Alloyed Ti-Nb Powders

2008 ◽  
Vol 591-593 ◽  
pp. 141-146 ◽  
Author(s):  
Y.A. Giffoni ◽  
Erika Coaglia Trindade Ramos ◽  
Hugo Ricardo Zschommler Sandim ◽  
M.T.T. Pacheco ◽  
Gilbert Silva ◽  
...  
Keyword(s):  
Ball Milling ◽  
Energy Dispersive Spectrometry ◽  
Structural Heterogeneity ◽  
Milling Process ◽  
X Ray Diffraction ◽  
Mechanically Alloyed ◽  
Structural Evaluation ◽  
Crystallite Sizes ◽  
Homogeneous Structures ◽  
Final Amount

This work discusses on the structural evaluation of mechanically alloyed Ti-Nb powders. The Nb amount was varied between 20 and 50 wt-%. The milling process was carried out in a planetary Fritsch P-5 ball mill under Ar atmosphere. The structural evaluation was conducted by scanning electron microscopy, X-ray diffraction, and energy dispersive spectrometry. During ball milling it was noted an excessive agglomeration of ductile Ti-Nb powders on the balls and vial surfaces, and the final amount of remaining powders was then drastically reduced into the vials. This fact was more pronounced with the increased Nb amount in starting powders. Typical lamella structures were formed during ball milling, which were refined for the longest milling times, and fine and homogeneous structures were formed in Ti-Nb (Nb=20-50wt-%) powders. XRD results indicated that the full width at half maximum values of Ti peaks were continuously increased while that the crystallite sizes were reduced for longer milling times due to the severe plastic deformation provided during ball milling of Ti-Nb powders. However, the EDS analysis revealed the presence of Nb-rich regions in Ti-Nb powders after ball milling. The critical ball milling behavior of ductile Ti- Nb powders contributed for reducing the yield powder and increasing the structural heterogeneity.

Phase Transformation in Mechanically Alloyed and Hot-Pressed Ti-2Nb-22Si-11B and Ti-6Nb-22Si-11B Powder Mixtures

2014 ◽  
Vol 802 ◽  
pp. 9-13 ◽  
Author(s):  
Andrezza Campos Zanardo ◽  
Neide Aparecida Mariano ◽  
Luciano Braga Alkmin ◽  
Alex Matos da Silva Costa ◽  
Carlos Angelo Nunes ◽  
...  
Keyword(s):  
Phase Transformation ◽  
Hot Pressing ◽  
Energy Dispersive Spectrometry ◽  
Weight Ratio ◽  
Milling Process ◽  
X Ray Diffraction ◽  
Mechanically Alloyed ◽  
Powder Mixtures ◽  
Eds Analysis ◽  
Rotary Speed

This work aims to discuss on the phase transformation in mechanically alloyed and hot-pressed Ti-2Nb-22Si-11B and Ti-6Nb-22Si-11B powder mixtures. The milling process was conducted in a planetary ball milling using stainless steel vials (225 mL) and balls (19 mm diameter), rotary speed of 300 rpm, and a ball-to-powder weight ratio of 10:1. Hot pressing of mechanically alloyed Ti-Nb-Si-B powders was performed under vacuum at 1100°C for 1h. The as-milled and hot-pressed Ti-Nb-Si-B samples were evaluated by X-ray diffraction, scanning electron microscopy, and energy dispersive spectrometry. XRD results of milled Ti-Nb-Si-B powders indicated that the peaks of Nb and Si were reduced for longer milling times, suggesting that Nb and Si atoms were dissolved into the Ti lattice to form extended solid solutions. Iron contamination close to 6 at% was detected by EDS analysis. Hot pressing produced dense and homogeneous samples containing a small amount of Ti6Si2B.

Phase Transformation in Mechanically Alloyed and Hot-Pressed Nb-4Si-8B and Nb-8Si-16B Alloys

2014 ◽  
Vol 802 ◽  
pp. 14-19
Author(s):  
Carlos Edilson Chiaradia ◽  
Luciano Braga Alkmin ◽  
Carlos Ângelo Nunes ◽  
Vinícius André Rodrigues Henriques ◽  
Gilda Maria Cortez Pereira ◽  
...  
Keyword(s):  
Phase Transformation ◽  
Energy Dispersive Spectrometry ◽  
Weight Ratio ◽  
Wet Milling ◽  
X Ray Diffraction ◽  
Mechanically Alloyed ◽  
X Ray ◽  
Equilibrium Structures ◽  
Steel Balls ◽  
Milled Powders

The work reports on the phase transformation in mechanically alloyed and hot-pressed Nb-4Si-8B and Nb-8Si-16B (at-%) alloys. Elemental powder mixtures were processed in a planetary ball mill under argon atmosphere using 300 rpm, stainless steel balls (19 mm diameter) and vials (225 mL), and a ball-to-powder weight ratio of 10:1. After dry milling for 7h, wet milling with isopropyl alcohol for more 20 min was adopted to increase the recovering of previously cold-welded Nb-4Si-8B powders. To obtain the equilibrium structures the as-milled powders were hot-pressed under vacuum at 1200oC for 1 h. The as-milled powders and hot-pressed samples were characterized by X-ray diffraction, scanning electron microscopy, and energy dispersive spectrometry. XRD results revealed the presence of metastable phases in as-milled Nb-Si-B powders. The hot pressing has produced dense Nb-Si-B samples, which were formed by the Nbss, Nb3B2and Fe2Nb phases beside of other unknown Si-rich phase.

Structural Evaluation of Ti-Cr-Si-B Powders Produced by High-Energy Ball Milling and Sintering

2017 ◽  
Vol 899 ◽  
pp. 499-504
Author(s):  
Luiz Otávio Vicentin Maruya ◽  
Paulo Atsushi Suzuki ◽  
Alfeu Saraiva Ramos
Keyword(s):  
Ball Milling ◽  
Weight Ratio ◽  
High Energy ◽  
Milling Process ◽  
Wet Milling ◽  
Mechanically Alloyed ◽  
Structural Evaluation ◽  
Structural Applications ◽  
Rotary Speed ◽  
Steel Balls

Multicomponent Ti6Si2B-based alloys are potentially attractive for structural applications due to the low Ti6Si2B crystallographic anisotropy, and their oxidation resistance are higher than the Ti5Si3-based alloys. There is a limited amount of information on effect of alloying on stability of Ti6Si2B. The present work reports on the structural evaluation during ball milling and subsequent sintering of Ti-2Cr-22Si-11B and Ti-7Cr-22Si-11B (at-%) powders. The milling process was carried out in a planetary Fritsch P-5 ball mill under Ar atmosphere using hardened steel balls (19 mm diameter), stainless steel vials (225 mL), rotary speed of 300 rpm, and a ball-to-powder weight ratio of 10:1. Samples were collected after different milling times: 20, 60, 180, 300, 420 and 600 min. Addicional wet milling (isopropyl alcohol) for 20 more minutes was adopted to increase the yield powder into the vials. Following, the powders milled for 620 min were uniaxially compacted (20 MPa) in order to obtain cilinder green bodies with 10 mm diameter and subsequently sintered under vacuum at 1100°C for 240 min. The milled powders were characterized by X-ray diffraction, and scanning electron microscopy. The chromium addition have contributed to form a large amount of Ti6Si2B in the mechanically alloyed and sintered Ti-2Cr-22Si-11B and Ti-7Cr-22Si-11B alloys.

Syntheses of the Ni3Ti, NiTi, and NiTi2 Compounds by Mechanical Alloying

2006 ◽  
Vol 530-531 ◽  
pp. 217-222 ◽  
Author(s):  
C.B. Martins ◽  
Bruno Bacci Fernandes ◽  
Erika Coaglia Trindade Ramos ◽  
Gilbert Silva ◽  
Alfeu Saraiva Ramos
Keyword(s):  
Mechanical Alloying ◽  
Weight Ratio ◽  
Milling Process ◽  
X Ray Diffraction ◽  
Heat Treated ◽  
Amorphous Structures ◽  
Rotary Speed ◽  
Steel Balls ◽  
Ti Powder ◽  
Milled Powders

The aim of this work is to prepare the Ni3Ti, NiTi, and NiTi2 compounds by mechanical alloying from elemental Ni-25at.%Ti, Ni-50at.%Ti, and Ni-66.6at.%Ti powder mixtures. The milling process was carried out in a planetary ball mill under argon atmosphere using a rotary speed of 200rpm, stainless steel balls (10 and 19 mm diameters) and vials (225mL), and a ball-to-powder weight ratio of 10:1. Following, the milled powders were heat treated at 900oC for 1h in order to attain the equilibrium microstructures. The milled powders were characterized by means of X-ray diffraction (XRD), scanning electron microscopy (SEM), and microanalysis via EDS. Similar ball milling behavior of Ni-Ti powders was noted in this work, e.g., a pronounced cold-welding between ductile powders occurred during the initial milling times. The Ni3Ti, NiTi, and NiTi2 compounds were synthesized after milling for 30h. Atomic disordering of the NiTi and NiTi2 compounds was achieved, and amorphous structures were then formed in Ni-50Ti e Ni-66.6Ti powders milled for 60h and 210h, respectively. Homogeneous matrixes constituted by the Ni3Ti, NiTi, and NiTi2 phases were formed in Ni-Ti powders after heat treatments at 900oC for 1h. Iron contamination lower than 2 at-% was measured by EDS analysis in heat-treated Ni-Ti alloys.

Microstructure and Oxidation Resistance of Mechanically Alloyed and Sintered Ni-Nb and Ni-Nb-Ta Alloys

2017 ◽  
Vol 899 ◽  
pp. 19-24
Author(s):  
Lucas Moreira Ferreira ◽  
Stephania Capellari Rezende ◽  
Antonio Augusto Araújo Pinto da Silva ◽  
Gael Yves Poirier ◽  
Gilberto Carvalho Coelho ◽  
...  
Keyword(s):  
Ball Milling ◽  
Oxidation Resistance ◽  
Energy Dispersive Spectrometry ◽  
High Energy ◽  
Milling Process ◽  
Ternary Alloys ◽  
X Ray Diffraction ◽  
Mechanically Alloyed ◽  
Static Oxidation ◽  
Energy Ball

The present work reports on the microstructure and oxidation resistance of Ni-25Nb, Ni-20Nb-5Ta and Ni-15Nb-10Ta alloys produced by high-energy ball milling and subsequent sintering. The sintered samples were characterized by optical microscopy, scanning electron microscopy, X-ray diffraction, energy dispersive spectrometry, and static oxidation tests. Homogeneous microstructures of the binary and ternary alloys indicated the major presence of the β-Ni3Nb compound as matrix, which dissolved large amounts of tantalum. Consequently, the β-Ni3Nb peaks moved toward the direction of smaller diffraction angles. Iron contamination lower than 6.7 at.-% was detected by EDS analysis, which were picked-up during the previous ball milling process. After the static oxidation tests (1100°C for 4 h) the sintered Ni-25Nb, Ni-20Nb-5Ta and Ni-15Nb-10Ta alloys presented mass gains of 31.5%, 30.5% and 28.8%, respectively. Despite the higher densification of the Ni-15Nb-10Ta alloy, the results suggested that the tantalum addition contributed to improve the oxidation resistance of the β-Ni3Nb compound.

Effect of Milling Speed on the Synthesis of In-Situ Cu-25 Vol. % WC Nanocomposite by Mechanical Alloying

2012 ◽  
Vol 59 (2) ◽  
Author(s):  
Nurulhuda Bashirom ◽  
Nurzatil Ismah Mohd Arif
Keyword(s):  
Stainless Steel ◽  
Mechanical Alloying ◽  
Weight Ratio ◽  
High Energy ◽  
Milling Process ◽  
Nominal Composition ◽  
X Ray Diffraction ◽  
The Matrix ◽  
Steel Balls

This paper presents a study on the effect of milling speed on the synthesis of Cu-WC nanocomposites by mechanical alloying (MA). The Cu-WC nanocomposite with nominal composition of 25 vol.% of WC was produced in-situ via MA from elemental powders of copper (Cu), tungsten (W), and graphite (C). These powders were milled in the high-energy “Pulverisette 6” planetary ball mill according to composition Cu-34.90 wt% W-2.28 wt% C. The powders were milled in different milling speed; 400 rpm, 500 rpm, and 600 rpm. The milling process was conducted under argon atmosphere by using a stainless steel vial and 10 mm diameter of stainless steel balls, with ball-to-powder weight ratio (BPR) 10:1. The as-milled powders were characterized by X-Ray Diffraction (XRD) and Scanning Electron Microscopy (SEM). XRD result showed the formation of W2C phase after milling for 400 rpm and as the speed increased, the peak was broadened. No WC phase was detected after milling. Increasing the milling speed resulted in smaller crystallite size of Cu and proven to be in nanosized. Based on SEM result, higher milling speed leads to the refinement of hard W particles in the Cu matrix. Up to the 600 rpm, the unreacted W particles still existed in the matrix showing 20 hours milling time was not sufficient to completely dissolve the W.

On the Phase Transformation in Mechanically Alloyed Ni-Nb and Ni-Ta and Ni-Nb-Ta Powders

2012 ◽  
Vol 727-728 ◽  
pp. 222-226 ◽  
Author(s):  
Ana Clara Ferraretto ◽  
Erika Coaglia Trindade Ramos ◽  
Alfeu Saraiva Ramos
Keyword(s):  
Phase Transformation ◽  
Ball Milling ◽  
High Energy ◽  
Milling Process ◽  
Spontaneous Ignition ◽  
X Ray Diffraction ◽  
Mechanically Alloyed ◽  
Energy Ball ◽  
Rotary Speed ◽  
Steel Balls

This paper reports on the phase transformation during the preparation of Ni-25Nb, Ni-25Ta, Ni-20Nb-5Ta and Ni-15Nb-10Ta (at-%) powders by high-energy ball milling from elemental powders. The milling process was performed in a planetary ball milling using stainless steel balls and vials, rotary speed of 300rpm, and a ball-to-powder of 10:1. To minimize contamination and spontaneous ignition the powders were handled under argon atmosphere in a glove box. The milled powders were characterized by means of X-ray diffraction techniques. Results indicated that the Ni atoms were preferentially dissolved into the Nb (and/or Ta) lattice at the initial milling times, which contributed to change the relative intensity on the diffraction peaks. After the dissolution of Nb (and/or Ta) into the Ni lattice, the Ni peaks were moved to the direction of lower diffraction angles in Ni-25Nb, Ni-25Ta, Ni-20Nb-5Ta, Ni-15Nb-10Ta powders, indicating that the mechanical alloying was achieved. .

Phase Transformations in Mechanically Alloyed and Sintered Ti-XMg-22Si-11B (X = 2 and 7 at.-%at) Powders

2017 ◽  
Vol 899 ◽  
pp. 3-8
Author(s):  
Luiz Otávio Vicentin Maruya ◽  
Bruno Bacci Fernandes ◽  
Mario Ueda ◽  
Alfeu Saraiva Ramos
Keyword(s):  
Ball Milling ◽  
Energy Dispersive Spectrometry ◽  
Weight Ratio ◽  
High Energy ◽  
X Ray Diffraction ◽  
Amorphous Halo ◽  
Mechanically Alloyed ◽  
X Ray ◽  
Equilibrium Structures ◽  
Energy Ball

This work reports on effect of magnesium addition on the Ti6Si2B stability in Ti-xMg-22Si-11B (x = 2 and 6 at.-%) alloys prepared by high-energy ball milling and subsequent sintering. Ball milling was conducted under Ar atmosphere in stainless steel vials and balls, 300 rpm, and a ball-to-powder weight ratio of 10:1. Following, the powders milled for 10 h were axially compacted in order to obtain cylinder samples with 6 mm diameter. To obtain the equilibrium structures the green samples were sintered at 1100°C for 4 h under Ar atmosphere. X-ray diffraction, scanning electron microscopy and energy dispersive spectrometry were used to characterize the as-milled powders and sintered samples. Extended Ti solid solution were found in the Ti-2Mg-22Si-11B and Ti-7-Mg-Si-B powders milled for 20 min and 60 min, respectively, whereas an amorphous halo was produced on Ti-2Mg-22Si-11B powders milled for 420 min. The increase of Mg amount in the starting powder mixture has inhibited the Ti6Si2B formation in the mechanically alloyed and sintered Ti-7Mg-22Si-11B alloy.

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