Effect of tungsten reinforcement on mechanical, tribological and corrosion behaviour of mechanically alloyed Co-25C Cermet nanocomposites

Elemental powders of Nd, Fe and B were mechanically alloyed using a planetary ball mill. The change of structure and particle size was examined. XRD pattern revealed that with prolong milling, the mixture of the powders was transformed to nearly amorphous state. Smaller particle size was observed with prolong milling. Magnetization of the mixture of powders was studied using AGM. The saturation magnetization of the mixture was observed to increase initially and then decrease with increasing milling time. The reduction of the magnetic properties was suspected to be due to surface damage which was incurred by extensive milling. The corrosion rate was observed to be higher for larger particle size (low milling time). This indicated higher mass gain percentage of larger particle size compared to lower particle size. The magnetic properties however, did not should any significant improvement after corrosion effect.

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Effect of Microstructural Modifications on the Corrosion Resistance of CoCrFeMo0.85Ni Compositionally Complex Alloy Coatings

Coatings ◽

10.3390/coatings9110695 ◽

2019 ◽

Vol 9 (11) ◽

pp. 695 ◽

Cited By ~ 1

Author(s):

Francesco Fanicchia ◽

Ioana Csaki ◽

Laura E. Geambazu ◽

Henry Begg ◽

Shiladitya Paul

Keyword(s):

Corrosion Resistance ◽

Corrosion Behaviour ◽

Electrochemical Corrosion ◽

Production Method ◽

Carbon Steels ◽

Face Centered Cubic ◽

Mechanically Alloyed ◽

Complex Alloy ◽

Powder Production ◽

Fcc Phase

A compositionally complex alloy (CCA) was developed in powder form and applied as a coating onto a carbon steels substrate by using thermal spray. The purpose of this study was to investigate the effect of microstructural modification induced by using two different powder production methods, mechanical alloying and gas atomisation, onto the corrosion resistance of the coatings for a CoCrFeMo0.85Ni composition. The evolution of microstructure from powders to coatings was analysed using scanning electron microscopy coupled with energy-dispersive spectroscopy and X-ray diffraction. In order to evaluate the corrosion performance of the coatings, electrochemical corrosion tests were performed in a 3.5 wt % NaCl solution at pH = 4. The study demonstrates that the powder production method has a significant influence on the phase composition and, in turn, corrosion behaviour of the resulting coating, with the gas atomising route imparting better corrosion resistance properties. Nevertheless, the appearance of the face-centered cubic (FCC) phase characteristic of the CoCrFeMo0.85Ni alloy within the coating produced from the mechanically alloyed powder, opens the possibility for this powder manufacturing technique to effectively produce compositionally complex alloys.

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Fine Microstructure of a Mechanically Alloyed Oxide Dispersion Strengthened Nickel-Base Superalloy

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100079012 ◽

1977 ◽

Vol 35 ◽

pp. 298-299

Author(s):

Jordi Marti ◽

Timothy E. Howson ◽

David Kratz ◽

John K. Tien

Keyword(s):

Solid Solution ◽

Volume Fraction ◽

Stress Rupture ◽

Oxide Dispersion Strengthened ◽

Solid Solution Alloy ◽

Oxide Dispersion ◽

Creep And Stress Rupture ◽

Mechanically Alloyed ◽

Fine Microstructure ◽

Nickel Base

The previous paper briefly described the fine microstructure of a mechanically alloyed oxide dispersion strengthened nickel-base solid solution. This note examines the fine microstructure of another mechanically alloyed system. This alloy differs from the one described previously in that it is more generously endowed with coherent precipitate γ forming elements A1 and Ti and it contains a higher volume fraction of the finely dispersed Y2O3 oxide. An interesting question to answer in the comparative study of the creep and stress rupture of these two ODS systems is the role of the precipitate γ' in the mechanisms of creep and stress rupture in alloys already containing oxide dispersoids.The nominal chemical composition of this alloy is Ni - 20%Cr - 2.5%Ti - 1.5% A1 - 1.3%Y203 by weight. The system receives a three stage heat treatment-- the first designed to produce a coarse grain structure similar to the solid solution alloy but with a smaller grain aspect ratio of about ten.

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Microstructure of mechanically alloyed and hot-pressed Al5CuZr2

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100177982 ◽

1990 ◽

Vol 48 (4) ◽

pp. 970-971

Author(s):

T. E. Mitchell ◽

P. B. Desch ◽

R. B. Schwarz

Keyword(s):

Mechanical Alloying ◽

Vickers Hardness ◽

Hot Pressing ◽

Rapid Quenching ◽

Hardened Steel ◽

Alloyed Powder ◽

Ion Milling ◽

Mechanical Grinding ◽

Mechanically Alloyed ◽

Steel Container

Al3Zr has the highest melting temperature (1580°C) among the tri-aluminide intermetal1ics. When prepared by casting, Al3Zr forms in the tetragonal DO23 structure but by rapid quenching or by mechanical alloying (MA) it can also be prepared in the metastable cubic L12 structure. The L12 structure can be stabilized to at least 1300°C by the addition of copper and other elements. We report a TEM study of the microstructure of bulk Al5CuZr2 prepared by hot pressing mechanically alloyed powder.MA was performed in a Spex 800 mixer using a hardened steel container and balls and adding hexane as a surfactant. Between 1.4 and 2.4 wt.% of the hexane decomposed during MA and was incorporated into the alloy. The mechanically alloyed powders were degassed in vacuum at 900°C. They were compacted in a ram press at 900°C into fully dense samples having Vickers hardness of 1025. TEM specimens were prepared by mechanical grinding followed by ion milling at 120 K. TEM was performed on a Philips CM30 at 300kV.

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Evaluation of corrosion behaviour of tantalum coating obtained by low pressure chemical vapor deposition using electrochemical polarization

Journal de Physique IV (Proceedings) ◽

10.1051/jp4:20020079 ◽

2002 ◽

Vol 12 (4) ◽

pp. 69-74 ◽

Cited By ~ 2

Author(s):

A. Levesque ◽

A. Bouteville ◽

H. de Baynast ◽

B. Laveissière

Keyword(s):

Chemical Vapor Deposition ◽

Vapor Deposition ◽

Corrosion Behaviour ◽

Chemical Vapor ◽

Low Pressure ◽

Electrochemical Polarization ◽

Pressure Chemical

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Role of Aluminium on the Microstructure and Corrosion Behaviour of Magnesium Prepared by Powder Metallurgy Method

International Journal of Automotive and Mechanical Engineering ◽

10.15282/ijame.17.3.2020.14.0618 ◽

2020 ◽

Vol 17 (3) ◽

pp. 8206-8213

Author(s):

J. Alias

Keyword(s):

Corrosion Resistance ◽

Powder Metallurgy ◽

Corrosion Behaviour ◽

Corrosion Current ◽

Optical Microscope ◽

High Reactivity ◽

Aluminium Content ◽

Powder Metallurgy Method ◽

X Ray Diffraction ◽

Promising Development

Much research on magnesium (Mg) emphasises creating good corrosion resistance of magnesium, due to its high reactivity in most environments. In this study, powder metallurgy (PM) technique is used to produce Mg samples with a variation of aluminium (Al) composition. The effect of aluminium composition on the microstructure development, including the phase analysis was characterised by optical microscope (OM), scanning electron microscopy (SEM) and x-ray diffraction (XRD). The mechanical property of Mg sample was performed through Vickers microhardness. The results showed that the addition of aluminium in the synthesised Mg sample formed distribution of Al-rich phases of Mg17Al12, with 50 wt.% of aluminium content in the Mg sample exhibited larger fraction and distribution of Al-rich phases as compared to the 20 wt.% and 10 wt.% of aluminium content. The microhardness values were also increased at 20 wt.% and 50 wt.% of aluminium content, comparable to the standard microhardness value of the annealed Mg. A similar trend in corrosion resistance of the Mg immersed in 3.5 wt.% NaCl solution was observed. The corrosion behaviour was evaluated based on potentiodynamic polarisation behaviour. The corrosion current density, icorr, is observed to decrease with the increase of Al composition in the Mg sample, corresponding to the increase in corrosion resistance due to the formation of aluminium oxide layer on the Al-rich surface that acted as the corrosion barrier. Overall, the inclusion of aluminium in this study demonstrates the promising development of high corrosion resistant Mg alloys.

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