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Article
Publication date: 9 October 2009

K.O. Sanusi and G.J. Oliver

Severe plastic deformation (SPD) has provided new opportunities in investigations of enhanced mechanical properties like high strength and ductility by permitting grain

1484

Abstract

Purpose

Severe plastic deformation (SPD) has provided new opportunities in investigations of enhanced mechanical properties like high strength and ductility by permitting grain refinement to a nanometer level, especially ultra‐fine grained and nanocrystalline metals and alloys. These materials have been attracting more and more research interest during the past few decades due to scientific curiosity and their engineering potentials with a significant advancement in their understanding. The purpose of this paper is to find the relationship between processing, structures and properties of these novel materials with the ultimate goal of producing a model to account for the grain size changes at the nano‐scale.

Design/methodology/approach

In this paper, specimens with various grain sizes from 23 to 80 μm are obtained via processing by SPD, using equal channel angular press (ECAP) technique. The effect of grain size on the hardness properties of nanostructured copper alloy has been investigated using micro‐hardness testing of the samples to test the mechanical properties of this material.

Findings

The results reveal that the copper alloys processed by SPD using ECAP technique after various passes differ in the grain size and mechanical properties. The hardness test exhibits grained size dependence according to Hall‐Petch relationship from room temperature. The increase in the hardness with number of passages suggest increasing in strain during deformation, as the passes increase the smaller grain size can be produced.

Originality/value

The paper usefully shows how nanostructured materials by SPD technique will offer a possible solution to the problem of using light metals for certain applications by increasing the strength of materials which could be used in structures where previously strength requirement in various industries, including such as, for example, transportation, medical devices and electronics. Understanding the relationship between processing, structures and properties will enhance the performance of metals and alloys in a target application which is important in improving the mechanical properties of engineering materials that are necessary fundamental for applications of lightweight materials and structures. The influences of structural parameters, such as grain size, grain shape on plastic deformation which is important parameters in study the mechanical properties of nanostructured materials.

Details

Journal of Engineering, Design and Technology, vol. 7 no. 3
Type: Research Article
ISSN: 1726-0531

Keywords

Article
Publication date: 16 June 2022

Jun Zhu, Wei Luo, Wentao Xv, Shuigen Xv, XinYang Zhang and Jiefang Zhao

This paper aims to study the electrochemical corrosion performance of ultrafine-grained (UFG) Cu bulk in 0.5 M NaCl solution.

Abstract

Purpose

This paper aims to study the electrochemical corrosion performance of ultrafine-grained (UFG) Cu bulk in 0.5 M NaCl solution.

Design/methodology/approach

UFG Cu bulk were prepared by impacting at −196°C and following heat treatment. The electrochemical corrosion behaviors of coarse-grained (CG), impacted and subsequently annealed at 190°C Cu bulks were studied.

Findings

All the bulks displayed typical active-passive-transpassive behaviors (dual passive films without stable passive regions). The resistance to corrosion of impacted Cu bulk was notably superior to that of CG Cu bulk, and subsequently annealing further improved its corrosion resistance.

Social implications

Except for mechanical properties, corrosion performance has been considered to be one of the most important aspects in bulk UFG metallic materials research for the prospective engineering applications.

Originality/value

Cryogenic impacting could effectively reduce grain size of CG Cu bulk to UFG scale and induce high density dislocation. Subsequent annealing resulted in a further decrease of grain size even to nanoscale, as well as nanometer twins. The grain refinement, high density dislocation and annealing twins effectively enhance the passivation capability, resulting in an increase in the corrosion resistance.

Details

Anti-Corrosion Methods and Materials, vol. 69 no. 5
Type: Research Article
ISSN: 0003-5599

Keywords

Article
Publication date: 17 May 2022

Ahmed Bouchekhlal and Mohammed Boulesbaa

The purpose of this paper is to investigate the effects of the sintering temperature on the microstructural, morphological and electrical characteristics of Zinc oxide…

Abstract

Purpose

The purpose of this paper is to investigate the effects of the sintering temperature on the microstructural, morphological and electrical characteristics of Zinc oxide (ZnO)-based varistors.

Design/methodology/approach

This study used a conventional method to design and produce ZnO varistors by sintering ZnO powder with small amounts of various metal oxides. Furthermore, the effect of sintering temperature on varistor properties of (Bi, Co, Cr, Sb, Mn)-doped ZnO ceramics was investigated in the range of 1280–1350 °C.

Findings

The obtained results showed an EB value of 2109.79 V/cm, a Vgb value of 0.831 V and a nonlinear coefficient (α) value of 19.91 for sample sintered at temperature of 1300 °C. In addition, the low value of tan δ at low frequency range confirmed that the grain boundaries created in 1300 °C sintering temperature were obviously good.

Originality/value

Based on the previous research on the ZnO-based varistors, a thorough study was carried out on these components to improve their electrical characteristics. Thus, it is necessary that those varistors have low leakage current and low value of dissipation factor to ensure their good quality. High breakdown fields and nonlinearity coefficients are also required in such kind of components. The effect of sintering temperature on the varistor properties of the new compositions (zinc, bismuth, manganese, chrome, cobalt, antimony and silicon oxides)-doped ZnO ceramics was studied in the range of 1280–1350 °C. Also, the microstructure and the phase evolution of the samples sintered at various temperatures (1280 °C, 1300 °C, 1320 °C and 1350 °C) were investigated according to X-ray diffraction and scanning electron microscope measurements.

Details

Microelectronics International, vol. 39 no. 3
Type: Research Article
ISSN: 1356-5362

Keywords

Article
Publication date: 3 April 2017

Izhan Abdullah, Muhammad Nubli Zulkifli, Azman Jalar and Roslina Ismail

The purpose of this paper is to investigate the relationship between microstructure and varied strain rates towards the mechanical properties and deformation behaviour of…

Abstract

Purpose

The purpose of this paper is to investigate the relationship between microstructure and varied strain rates towards the mechanical properties and deformation behaviour of Sn-3.0Ag-0.5Cu (SAC305) lead-free solder wire at room temperature.

Design/methodology/approach

Tensile tests with different strain rates of 1.5 × 10−6, 1.5 × 10−5, 1.5 × 10−4, 1.5 × 10−3, 1.5 × 10−2 and 1.5 × 10−1 s−1 at room temperature of 25°C were carried out on lead-free Sn-3.0Ag-0.5Cu (SAC305) solder wire. Stress-strain curves and mechanical properties such as yield strength, ultimate tensile strength and elongation were determined from the tensile tests. A microstructure analysis was performed by measuring the average grain size and the aspect ratio of the grains.

Findings

It was observed that higher strain rates showed pronounced dynamic recrystallization on the stress-strain curve. The increase in the strain rates also decreased the grain size of the SAC305 solder wire. It was found that higher strain rates had a pronounced effect on changing the deformation or shape of the grain in a longitudinal direction. An increase in the strain rates increased the tensile strength and ductility of the SAC solder wire. The primary deformation mechanism for strain rates below 1.5 × 10−1 s−1 was grain boundary sliding, whereas the deformation mechanism for strain rates of 1.5 × 10−1 s−1 was diffusional creep.

Originality/value

Most of the studies regarding the deformation behaviour of lead-free solder usually consider the effect of the elevated temperature. For the current analysis, the effect of the temperature is kept constant at room temperature to analyze the deformation of lead-free solder wire solely because of changes of strain rates, and this is the originality of this paper.

Details

Soldering & Surface Mount Technology, vol. 29 no. 2
Type: Research Article
ISSN: 0954-0911

Keywords

Article
Publication date: 2 January 2007

Y. Srinivasa Rao

The paper aims to study the variation of electrical properties like electrical resistivity and current noise of a polymer thick film resistor, namely, PVC‐graphite thick…

Abstract

Purpose

The paper aims to study the variation of electrical properties like electrical resistivity and current noise of a polymer thick film resistor, namely, PVC‐graphite thick film resistor, with parameters such as volume fraction, grain size, temperature and high voltage.

Design/methodology/approach

A model is proposed to explain the observed variations, which assumes that the texture of the polymer thick film resistor consists of insulator granules coated with conducting particles and also having cavities. The resistivity of these resistors is controlled mainly by the contact resistance between the conducting particles and the number of contacts each particle with its neighbors.

Findings

The variation of resistivity with temperature and high voltage is explained with the help of the model and it is attributed to the change in contact area and number of contacts. The current noise of these resistors is controlled mainly by the average relative resistance fluctuations between the conducting particles and the number of contacts each particle with its neighbors.

Originality/value

The variation of current noise with high voltage has also been explained with the help of this model and it is attributed to the change in number of conducting particles and conducting layers.

Details

Microelectronics International, vol. 24 no. 1
Type: Research Article
ISSN: 1356-5362

Keywords

Article
Publication date: 5 May 2015

Archana Rethinam, Vinoo D. Shivakumar, L. Harish, M.B. Abhishek, G.V. Ramana, Madhusudana R., R. Sah and S. Manjini

The application of new technologies requires, however, modern rolling mills. Indeed, in manufacturing plants of older types, strict compliance with the developed rolling…

Abstract

Purpose

The application of new technologies requires, however, modern rolling mills. Indeed, in manufacturing plants of older types, strict compliance with the developed rolling regimes is not always feasible. Improving the mechanical properties in such cases is possible only by means of cooling. Compressive deformation behavior of carbon–manganese (C-Mn) grade has been investigated at temperatures ranging from 800-900°C and strain rate from 0.01-50 s−1 on Gleeble-3800, a thermo-mechanical simulator. Simulation studies have been conducted mainly to observe the microstructural changes for various strain rate and deformation temperatures at a constant strain of 0.5 and a cooling rate of 20°C s−1.

Design/methodology/approach

The project begins with simulation of a hot rolling condition using the thermo-mechanical simulator; this was followed by microstructural examination and identification of phases present by using an optical microscope for hot-rolled coil and simulated samples; grain size measurement and size distribution studies; and optimization of finishing temperature, coiling temperature and cooling rate by mimicking plant processing parameters to improve the mechanical properties.

Findings

As the strain rate and temperature increase, pearlite banding decreases gradually and finally gets completely eliminated, thereby improving the mechanical properties. True stress–strain curves were plotted to extrapolate the effect of strain-hardening and strain rate sensitivity on austenite (γ) and austenite–ferrite (γ-a) regions. To validate the effect of strain rate and temperature over the grain size, the hardness of simulated samples was measured using the universal hardness tester and the corresponding tensile strength was found from the standard hardness chart.

Practical implications

The results of the study carried out have projected a new technology of thermo-mechanical simulation for the studied C-Mn grade. These results were used to optimize the plant processing parameter like finishing and coiling temperature and finishing stands strain rate.

Originality/value

By controlling the hot rolling conditions like finishing, coiling temperature and cooling rate, structures differing in mechanical properties can be obtained for the same material. Accurate understanding of a structure being formed when different temperatures are applied enables the control of the process that assures intended structures and mechanical properties are achieved.

Details

Journal of Engineering, Design and Technology, vol. 13 no. 2
Type: Research Article
ISSN: 1726-0531

Keywords

Article
Publication date: 1 February 2008

D.S. Antropov and M.S. Veshchunov

A new recently proposed mechanism of the lenticular grain face bubble migration which controls the bubble mobility and determines the drag force exerted on the grain

Abstract

A new recently proposed mechanism of the lenticular grain face bubble migration which controls the bubble mobility and determines the drag force exerted on the grain boundary, is further developed in application to the peripheral (edge and corner) intergranular bubbles. It is shown that contribution of the peripheral bubbles to the retarding effect can be significant, especially under irradiation conditions with high fission rates in UO2 fuel. In addition, simultaneous consideration of intergranular bubbles and pores evolution allows further improvement of the model predictions for grain growth under irradiation conditions. The improved model was implemented in the integral code MFPR, which is designed for modelling of fission product release from irradiated UO2 fuel, and validated against various tests under irradiation and annealing conditions with various types (dense and porous) fuel pellets.

Details

Multidiscipline Modeling in Materials and Structures, vol. 4 no. 2
Type: Research Article
ISSN: 1573-6105

Keywords

Article
Publication date: 9 September 2013

Fevzi Karsli and Mustafa Dihkan

The purpose of this paper is to provide crystal size distribution (CSD) using photogrammetric and image analysis techniques. A new algorithm is proposed to detect CSDs and…

Abstract

Purpose

The purpose of this paper is to provide crystal size distribution (CSD) using photogrammetric and image analysis techniques. A new algorithm is proposed to detect CSDs and a comparison is carried out with conventional watershed segmentation algorithm.

Design/methodology/approach

Polished granite plates were prepared to designate the metrics of CSD measurements. There are many important metrics for measurements on CSD. Some of them are orientation, size, position, area, aspect ratio, convexity, circularity, perimeter, convex hull, bounding box, eccentricity, shape, max-min length of CSD's fitted and corrected ellipse, and population density in a per unit area. Prior to image processing stage, camera calibration was performed to remove the image distortion errors. Image processing techniques were applied to corrected images for detecting the CSD parameters.

Findings

The proposed algorithm showed the improved preservation of size and shape characteristics of the crystal material when compared to the watershed segmentation. According to the experimental results, proposed algorithm revealed promising results in identifying CSDs more easily and efficiently.

Originality/value

This paper describes CSD of granitic rocks by using automated grain boundary detection methods in polished plate images. Some metrics of CSDs were detected by employing a new procedure. A computer-based image analysis technique was developed to measure the CSDs on the granitic rock plates. A validation is done by superimposing digitally detected CSD metrics to original samples.

Details

Sensor Review, vol. 33 no. 4
Type: Research Article
ISSN: 0260-2288

Keywords

Article
Publication date: 1 August 2003

Masayoshi Akiyama, Yutaka Neishi, Yoshitaka Adachi and Kenjiro Terada

Observation by optical microscopy and EBSP have made it clear that the trigger for the grain coarsening phenomenon of austenite stainless steel BS304S31 may be the…

Abstract

Observation by optical microscopy and EBSP have made it clear that the trigger for the grain coarsening phenomenon of austenite stainless steel BS304S31 may be the stacking faults concentrating selectively in a thin layer lying just beneath the grain boundary. When macroscopic plastic strain reached 6 percent, selective concentration of stacking faults was observed. When it reached 20 percent, the distribution of stacking faults became uniform in each grain. After these specimens were heated, concentration of stacking faults disappeared, and grain coarsening occurred at the point with 6 percent strain, but no grain coarsening occurred at the point with 20 percent strain. In order to investigate this concentration of stacking faults, an attempt was made to analyze the deformation in each crystal by using image‐based FEM. The result suggested that there is a possibility that plastic strain concentrates in the vicinity of the grain boundary when the macroscopic plastic strain is small.

Details

Engineering Computations, vol. 20 no. 5/6
Type: Research Article
ISSN: 0264-4401

Keywords

Article
Publication date: 27 November 2018

Fuda Ning, Yingbin Hu and Weilong Cong

The purpose of this paper is to identify if the implementation of ultrasonic vibration in laser engineered net shaping (LENS) process can help to reduce internal…

484

Abstract

Purpose

The purpose of this paper is to identify if the implementation of ultrasonic vibration in laser engineered net shaping (LENS) process can help to reduce internal weaknesses such as porosity, coarse primary TiB whisker and heterogeneous distribution of TiB reinforcement in the LENS-fabricated TiB reinforced Ti matrix composites (TiB-TMC) parts.

Design/methodology/approach

An experimental investigation is performed to achieve the results for comparative studies under different fabrication conditions through quantitative data analysis. An approach of microstructural characterization and mechanical testing is conducted to obtain the output attributes. In addition, the theoretical analysis of the physics of ultrasonic vibration in the melting materials is presented to explain the influences of ultrasonic vibration on the microstructural evolution occurred in the part fabrication.

Findings

Because of the nonlinear effects of acoustic streaming and cavitation induced by ultrasonic vibration, porosity is significantly reduced and a relatively small variation of pore sizes is achieved. Ultrasonic vibration also causes the formation of smaller TiB whiskers that distribute along grain boundaries with a homogeneous dispersion. Additionally, a quasi-continuous network (QCN) microstructure is considerably finer than that produced by LENS process without ultrasonic vibration. The refinements of both reinforcing TiB whiskers and QCN microstructural grains further improve the microhardness of TiB-TMC parts.

Originality/value

The novel ultrasonic vibration-assisted (UV-A) LENS process of TiB-TMC is conducted in this work for the first time to improve the process performance and part quality.

Details

Rapid Prototyping Journal, vol. 25 no. 3
Type: Research Article
ISSN: 1355-2546

Keywords

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