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Article
Publication date: 14 September 2011

Shenghai Wang and Chuncheng Yang

The microstructure difference and enthalpy changes have been investigated by scanning electron microscopy (SEM) and differential scanning calorimetry (DSC) during the…

Abstract

The microstructure difference and enthalpy changes have been investigated by scanning electron microscopy (SEM) and differential scanning calorimetry (DSC) during the as-cast ageing process. After the as-cast ageing process, the eutectic silicon and α-Al is in the ideal state for the alloy with 0.08 wt% mischmetal (MM) addition. The energy of the phase transformations is 5.8 J/g during the isothermal process, when Al-11%Si-0.27%Mg alloy is aged at 150°C. When the additive contents of MM are 0.03, 0.06, 0.08 and 0.1 wt%, respectively, the energies of phase transformations are 4.98, 1.39, 1.07 and 1.25 J/g correspondingly. It is shown that the energies of phase transformations decrease gradually as the MM content increases from 0 wt% to 0.08 wt%; the energies then increase upon further addition of the MM concentration from 0.08 wt% to 0.1 wt% in the as-cast ageing process. Furthermore, the beginning time of phase transformations is delayed with the MM addition.

Details

World Journal of Engineering, vol. 8 no. 3
Type: Research Article
ISSN: 1708-5284

Keywords

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Article
Publication date: 16 July 2021

Srinivas Prabhu, Padmakumar Bajakke and Vinayak Malik

In-situ aluminum metal matrix composites (AMMC) have taken over the use of ex-situ AMMC due to the generation of finer and thermodynamically stable intermetallic…

Abstract

Purpose

In-situ aluminum metal matrix composites (AMMC) have taken over the use of ex-situ AMMC due to the generation of finer and thermodynamically stable intermetallic compounds. However, conventional processing routes pose inevitable defects like porosity and agglomeration of particles. This paper aims to study current state of progress in in-situ AMMC fabricated by Friction Stir Processing.

Design/methodology/approach

Friction stir processing (FSP) has successfully evolved to be a favorable in-situ composite manufacturing technique. The dynamics of the process account for a higher plastic strain of 35 and a strain rate of 75 per second. These processing conditions are responsible for grain evolution from rolled grain → dislocation walls and dislocation tangles → subgrains → dislocation multiplication → new grains. Working of matrix and reinforcement under ultra-high strain rate and shorter exposure time to high temperatures produce ultra-fine grains. Do the grain evolution modes include subgrain boundaries → subgrain boundaries and high angle grain boundaries → high angle grain boundaries.

Findings

Further, the increased strain and strain rate can shave and disrupt the oxide layer on the surface of particles and enhance wettability between the constituents. The frictional heat generated by tool and workpiece interaction is sufficient enough to raise the temperature to facilitate the exothermic reaction between the constituents. The heat released during the exothermic reaction can even raise the temperature and accelerate the reaction kinetics. In addition, heat release may cause local melting of the matrix material which helps to form strong interfacial bonds.

Originality/value

This article critically reviews the state of the art in the fabrication of in-situ AMMC through FSP. Further, FSP as a primary process and post-processing technique in the synthesis of in-situ AMMC are also dealt with.

Details

World Journal of Engineering, vol. ahead-of-print no. ahead-of-print
Type: Research Article
ISSN: 1708-5284

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Article
Publication date: 1 November 1958

F.A. Kirk and J. Williams

This article, Part I of which appeared in last month's CORROSION TECHNOLOGY, is intended to provide a comparison of the corrosion‐and heat‐resistant steels specified in…

Abstract

This article, Part I of which appeared in last month's CORROSION TECHNOLOGY, is intended to provide a comparison of the corrosion‐and heat‐resistant steels specified in Great Britain and the U.S.A. for use in the Petroleum Industry. The article is a condensed version of the paper presented at the 1957 International Petroleum Equipment Conference.

Details

Anti-Corrosion Methods and Materials, vol. 5 no. 11
Type: Research Article
ISSN: 0003-5599

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Article
Publication date: 24 November 2020

Seyed Mohammad Hossein Mousavian, Seyed Hadi Tabaian and Mohammadhassan Badihehaghdam

The effect of zirconium, zinc, calcium and rare earth group as the alloying elements on mechanical properties and corrosion behavior of magnesium alloys was investigated…

Abstract

Purpose

The effect of zirconium, zinc, calcium and rare earth group as the alloying elements on mechanical properties and corrosion behavior of magnesium alloys was investigated in the simulated body fluid.

Design/methodology/approach

Pure magnesium and the alloying elements were melted and zirconium was finally added to obtain different alloys. The castings were annealed and some samples were aged heat treated. X-ray fluorescence was used for the elemental analysis and LSV was used for electrochemical corrosion evaluations.

Findings

Results showed that corrosion resistance decreases with increasing zirconium content. The lowest corrosion rate was obtained for the samples containing 0.3% and 0.45% of Zr from annealed and aging heat-treated samples, respectively. Yield stress enhances with increasing the zirconium content and degrades by the aging heat treatment.

Originality/value

These alloys were studied for the first time. Effect of casting without using protective flux and vacuum furnaces. Effect of annealing at 440°C for 2 h and artificial aging at 200°C for 16 h. Alloy’s electrochemical behavior on the body’s simulation environment has been investigated. Improvement of mechanical properties after annealing heat treatment by high zirconium percentage.

Details

Anti-Corrosion Methods and Materials, vol. 67 no. 6
Type: Research Article
ISSN: 0003-5599

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Article
Publication date: 1 May 2006

L. Dzib‐Pérez, J. González‐Sánchez, T. Pérez, A. Juárez and P. Bartolo‐Pérez

To study the corrosion resistance of the novel alloy Al‐12.6La (wt%) manufactured using directional solidification.

Abstract

Purpose

To study the corrosion resistance of the novel alloy Al‐12.6La (wt%) manufactured using directional solidification.

Design/methodology/approach

Samples fabricated using the Bridgman growth technique at three different withdrawal velocities were subjected to total immersion tests in distilled water and in 3.5 per cent NaCl solution and to DC polarisation tests in distilled water. XPS analyses conducted on samples after polarisation indicated the presence of an La compound in the non passive corrosion products film formed.

Findings

Anodic polarisation induced dissolution of the alloy with the formation of a non passive corrosion product film. During potentiodynamic polarisation, a sudden current increment occurred at a potential value that was more positive for samples solidified at higher rates. The corrosion resistance of this Al‐12.6%La alloy decreased as the solidification rate increased.

Originality/value

The results presented in this work are an insight to the understanding of the corrosion resistance and electrochemical behaviour of this alloy for future engineering applications and development.

Details

Anti-Corrosion Methods and Materials, vol. 53 no. 3
Type: Research Article
ISSN: 0003-5599

Keywords

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