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Article
Publication date: 16 November 2020

Riaz Muhammad and Umair Ali

This paper aims to analyze the effect of cerium addition on the microstructure and the mechanical properties of Tin-Silver-Copper (SAC) alloy. The mechanical properties and…

Abstract

Purpose

This paper aims to analyze the effect of cerium addition on the microstructure and the mechanical properties of Tin-Silver-Copper (SAC) alloy. The mechanical properties and refined microstructure of a solder joint are vital for the reliability and performance of electronics. SAC305 alloys are potential choices to use as lead-free solders because of their good properties as compared to the conventional Tin-Lead solder alloys. However, the presence of bulk intermetallic compounds (IMCs) in the microstructure of SAC305 alloys affects their overall performance. Therefore, addition of cerium restrains the growth of IMCs and refines the microstructure, hence improving the mechanical performance.

Design/methodology/approach

SAC305 alloy is doped with various composition of xCerium (x = 0.15, 0.35, 0.55, 0.75, 0.95) % by weight. Pure elements in powdered form were melted in the presence of argon with periodic stirring to ensure a uniform melted alloy. The molten alloy is then poured into a pre-heated die to obtain a tensile specimen. The yield strength and universal tensile strength were determined using a fixed strain rate of 10 mm per minute or 0.1667 mm s^(−1). The IMCs are identified using X-ray diffraction, whereas the elemental phase composition and microstructure evolution are, respectively, examined by using electron dispersive spectroscopy and scanning electron microscopy.

Findings

Improvement in the microstructure and mechanical properties is observed with 0.15% of cerium additions. The tensile test also showed that SAC305-0.15% cerium exhibits more stress-bearing capacity than other compositions. The 0.75% cerium doped alloy indicated some improvement because of a decrease in fracture dislocation regions, but microstructure refinement and the arrangement of IMCs are not those of 0.15% Ce. Different phases of Cu_6 Sn_5, Ag_3 Sn and CeSn_3 and ß-Sn are identified. Therefore, the addition of cerium in lower concentrations and presence of Ce-Sn IMCs improved the grain boundary structure and resulted refinement in the microstructure of the alloy, as well as an enhancement in the mechanical properties.

Originality/value

Characterization of microstructure and evaluation of mechanical properties are carried out to investigate the different composition of SAC305-xCerium alloys. Finally, an optimized cerium composition is selected for solder joint in electronics.

Details

Soldering & Surface Mount Technology, vol. 33 no. 4
Type: Research Article
ISSN: 0954-0911

Keywords

Article
Publication date: 29 May 2009

Luca Facchini, Emanuele Magalini, Pierfrancesco Robotti and Alberto Molinari

The purpose of this paper is the microstructural and mechanical characterization of a biomedical Ti‐6Al‐4V alloy produced by electron beam melting, and the study of the stability…

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Abstract

Purpose

The purpose of this paper is the microstructural and mechanical characterization of a biomedical Ti‐6Al‐4V alloy produced by electron beam melting, and the study of the stability of the as‐built microstructure upon heat treatment.

Design/methodology/approach

Ti‐6Al‐4V alloy produced by electron beam melting has been mechanically characterized through tensile and fatigue testing. Its microstructure has been investigated by optical observation after etching and by X‐ray diffractometry analysis. The stability of the microstructure of the as‐built material has been deepened carrying out suitable heat treatments, after an analysis by dilatometry test.

Findings

The microstructure of a Ti‐6Al‐4V alloy produced by electron beam melting has a very fine and acicular morphology, because of the intrinsically high‐solidification rate of the process. This microstructure is very stable, and the traditional thermal treatments cannot modify it; the microstructure changes significantly only when an amount of strain is introduced in the material. However, the mechanical properties of the alloy produced by electron beam melting are good.

Originality/value

The paper provides evidence of the microstructural stability of the material produced by electron beam melting. Even if the microstructure of the as‐built material is not recommended by the specific ISO standard, the related mechanical properties are fully satisfactory. This is a significant indication from the point of view of the production of Ti‐6Al‐4V orthopaedic and dental prostheses by electron beam melting.

Details

Rapid Prototyping Journal, vol. 15 no. 3
Type: Research Article
ISSN: 1355-2546

Keywords

Article
Publication date: 11 June 2019

Amitava Choudhury, Snehanshu Pal, Ruchira Naskar and Amitava Basumallick

The purpose of this paper is to develop an automated phase segmentation model from complex microstructure. The mechanical and physical properties of metals and alloys are…

Abstract

Purpose

The purpose of this paper is to develop an automated phase segmentation model from complex microstructure. The mechanical and physical properties of metals and alloys are influenced by their microstructure, and therefore the investigation of microstructure is essential. Coexistence of random or sometimes patterned distribution of different microstructural features such as phase, grains and defects makes microstructure highly complex, and accordingly identification or recognition of individual phase, grains and defects within a microstructure is difficult.

Design/methodology/approach

In this perspective, computer vision and image processing techniques are effective to help in understanding and proper interpretation of microscopic image. Microstructure-based image processing mainly focuses on image segmentation, boundary detection and grain size approximation. In this paper, a new approach is presented for automated phase segmentation from 2D microstructure images. The benefit of the proposed work is to identify dominated phase from complex microstructure images. The proposed model is trained and tested with 373 different ultra-high carbon steel (UHCS) microscopic images.

Findings

In this paper, Sobel and Watershed transformation algorithms are used for identification of dominating phases, and deep learning model has been used for identification of phase class from microstructural images.

Originality/value

For the first time, the authors have implemented edge detection followed by watershed segmentation and deep learning (convolutional neural network) to identify phases of UHCS microstructure.

Details

Engineering Computations, vol. 36 no. 6
Type: Research Article
ISSN: 0264-4401

Keywords

Article
Publication date: 1 April 2006

Furen Xiao, Bo Liao, Guiying Qiao, Chunling Zhang, Yiyin Shan, Yong Zhong and Ke Yang

As an optimal microstructure of pipeline steels, acicular ferrite is widely found in steels used in oil and gas pipeline transportation because it possesses both high strength and…

Abstract

As an optimal microstructure of pipeline steels, acicular ferrite is widely found in steels used in oil and gas pipeline transportation because it possesses both high strength and good toughness. In this paper, the microstructure of acicular ferrite and its continuous cooling transformation (CCT) diagrams of six steels with different carbon and alloy additions have been studied by using dilatometry, optical metallography. And the effects of different hot deformation processes on the CCT diagrams and microstructures have also been studied. Furthermore, the effects of microalloyed elements and hot deformation on continuous cooling transformation have been discussed. The results show that lower carbon content and alloy additions such as Mn, Nb, Ti, Mo, Ni and/or Cu in steels will promote the formation of acicular ferrite. The hot deformation promotes the acicular ferrite transformation and refines the microstructures of final products.

Details

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

Keywords

Article
Publication date: 19 October 2023

Anuj Kumar and Mukul Shukla

Understanding and tailoring the solidification characteristics and microstructure evolution in as-built parts fabricated by laser powder bed fusion (LPBF) is crucial as they…

Abstract

Purpose

Understanding and tailoring the solidification characteristics and microstructure evolution in as-built parts fabricated by laser powder bed fusion (LPBF) is crucial as they influence the final properties. Experimental approaches to address this issue are time and capital-intensive. This study aims to develop an efficient numerical modeling approach to develop the process–structure (P-S) linkage for LPBF-processed Inconel 718.

Design/methodology/approach

In this study, a numerical approach based on the finite element method and cellular automata was used to model the multilayer, multitrack LPBF build for predicting the solidification characteristics (thermal gradient G and solidification rate R) and the average grain size. Validations from published experimental studies were also carried out to ensure the reliability of the proposed numerical approach. Furthermore, microstructure simulations were used to develop P-S linkage by evaluating the effects of key LPBF process parameters on G × R, G/R and average grain size. A solidification or G-R map was also developed to comprehend the P-S linkage.

Findings

It was concluded from the developed G-R map that low laser power and high scan speed will result in a finer microstructure due to an increase in G × R, but due to a decrease in G/R, columnar characteristics are also reduced. Moreover, increasing the layer thickness and decreasing the hatch spacing lowers the G × R, raises the G/R and generates a coarse columnar microstructure.

Originality/value

The proposed numerical modeling approach was used to parametrically investigate the effect of LPBF parameters on the resulting microstructure. A G-R map was also developed that enables the tailoring of the as-built LPBF microstructure through solidification characteristics by tuning the process parameters.

Details

Rapid Prototyping Journal, vol. 30 no. 2
Type: Research Article
ISSN: 1355-2546

Keywords

Article
Publication date: 18 July 2023

Bin Chen, Yuan Wang, Shaoqing Cui, Jiansheng Xiang, John-Paul Latham and Jinlong Fu

Accurate presentation of the rock microstructure is critical to the grain-scale analysis of rock deformation and failure in numerical modelling. 3D granite microstructure

Abstract

Purpose

Accurate presentation of the rock microstructure is critical to the grain-scale analysis of rock deformation and failure in numerical modelling. 3D granite microstructure modelling has only been used in limited studies with the mineral pattern often remaining poorly constructed. In this study, the authors developed a new approach for generating 2D and 3D granite microstructure models from a 2D image by combining a heterogeneous material reconstruction method (simulated annealing method) with Voronoi tessellation.

Design/methodology/approach

More specifically, the stochastic information in the 2D image is first extracted using the two-point correlation function (TPCF). Then an initial 2D or 3D Voronoi diagram with a random distribution of the minerals is generated and optimised using a simulated annealing method until the corresponding TPCF is consistent with that in the 2D image. The generated microstructure model accurately inherits the stochastic information (e.g. volume fraction and mineral pattern) from the 2D image. Lastly, the authors compared the topological characteristics and mechanical properties of the 2D and 3D reconstructed microstructure models with the model obtained by direct mapping from the 2D image of a real rock sample.

Findings

The good agreements between the mapped and reconstructed models indicate the accuracy of the reconstructed microstructure models on topological characteristics and mechanical properties.

Originality/value

The newly developed reconstruction method successfully transfers the mineral pattern from a granite sample into the 2D and 3D Voronoi-based microstructure models ready for use in grain-scale modelling.

Details

Engineering Computations, vol. 40 no. 6
Type: Research Article
ISSN: 0264-4401

Keywords

Article
Publication date: 16 January 2009

Jae‐Won Choi, Ryan B. Wicker, Seok‐Hyun Cho, Chang‐Sik Ha and Seok‐Hee Lee

The paper's aim is to explore a method using light absorption for improving manufacturing of complex, three‐dimensional (3D) micro‐parts with a previously developed dynamic mask…

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Abstract

Purpose

The paper's aim is to explore a method using light absorption for improving manufacturing of complex, three‐dimensional (3D) micro‐parts with a previously developed dynamic mask projection microstereolithography (MSL) system. A common issue with stereolithography systems and especially important in MSL is uncontrolled penetration of the ultraviolet light source into the photocrosslinkable resin when fabricating down‐facing surfaces. To accurately fabricate complex 3D parts with down‐facing surfaces, a chemical light absorber, Tinuvin 327™ was mixed in different concentrations into an acrylate‐based photocurable resin, and the solutions were tested for cure depths and successful micro‐part fabrication.

Design/methodology/approach

Tinuvin 327 was selected as the light absorber based on its high absorption characteristics (∼0.4) at 365 nm (the filtered light wavelength used in the MSL system). Four concentrations of Tinuvin 327 in resin were used (0.00, 0.05, 0.10, and 0.15 percent (w/w)), and cure depth experiments were performed. To investigate the effects of different concentrations of Tinuvin 327 on complex 3D microstructure fabrication, several microstructures with overhanging features such as a fan and spring were fabricated.

Findings

Results showed that higher concentrations of Tinuvin 327 reduced penetration depths and thus cure depths. For the resin with 0.15 percent (w/w) of the Tinuvin 327, a cure depth of ∼30 μm was achieved as compared to ∼200 μm without the light absorber. The four resin solutions were used to fabricate complex 3D microstructures, and different concentrations of Tinuvin 327 at a given irradiance and exposure energy were required for successful fabrication depending on the geometry of the micro‐part (concentrations of 0.05 and 0.1 percent (w/w) provided the most accurate builds for the fan and spring, respectively).

Research limitations/implications

Although two different concentrations of light absorber in solution were required to demonstrate successful fabrication for two different micro‐part geometries (a fan and spring), the experiments were performed using a single irradiance and exposure energy. A single solution with the light absorber could have possibly been used to fabricate these micro‐parts by varying irradiance and/or exposure energy, although the effects of varying these parameters on geometric accuracy, mechanical strength, overall manufacturing time, and other variables were not explored.

Originality/value

This work systematically investigated 3D microstructure fabrication using different concentrations of a light absorber in solution, and demonstrated that different light absorption characteristics were required for different down‐facing micro‐features.

Details

Rapid Prototyping Journal, vol. 15 no. 1
Type: Research Article
ISSN: 1355-2546

Keywords

Article
Publication date: 5 December 2016

Pawel Kucharczyk and Sebastian Münstermann

The purpose of this paper is to determine local properties in a coarse grain zone of 10 mm thick butt welded joints made of structural S355 and high strength S960 steels…

Abstract

Purpose

The purpose of this paper is to determine local properties in a coarse grain zone of 10 mm thick butt welded joints made of structural S355 and high strength S960 steels. Metallographic analyses showed that the width of the investigated zone for both S355 and S960 weldments was too small for direct sampling. Therefore, samples with reproduced microstructure were manufactured by heat treatment taking into account chemical composition and cooling conditions of weldments.

Design/methodology/approach

The basis for the heat treatment was the time-temperature-transition (TTT) curve, whose shape is defined by welding and cooling parameters. In this study the TTT curve was determined experimentally during welding as well as numerically simulated using SYSWELD program. The work pieces were heat-treated according to the TTT curves using thermomechanical treatment simulator and evaluated in terms of microstructure and micro hardness distribution. Finally, the secondary specimens were manufactured and investigated in monotonic tensile tests.

Findings

The presented approach allows for the determination of the local properties of welded joints. In this study mechanical properties (stress-strain curves) of heat affected zone (HAZ) were successfully estimated using samples with reproduced microstructure. Furthermore, it was found out that the chemical composition in the HAZ was not influenced by the welding process. Thus, the HAZ microstructure can be successfully reproduced using base material. Additionally, the paper contains recommendations for simulation of the local microstructure and suggestions for the evaluation of the obtained results.

Originality/value

The advantage of the proposed approach is the enlargement of the material volume with homogeneous microstructure so that different local properties like toughness, fatigue behavior, crack propagation or crashworthiness can be analyzed, what is technically infeasible for the weldments with small HAZ.

Details

International Journal of Structural Integrity, vol. 7 no. 6
Type: Research Article
ISSN: 1757-9864

Keywords

Article
Publication date: 24 June 2021

Rafael Kakitani, Cassio Augusto Pinto da Silva, Bismarck Silva, Amauri Garcia, Noé Cheung and José Eduardo Spinelli

Overall, selection maps about the extent of the eutectic growth projects the solidification velocities leading to given microstructures. This is because of limitations of most of…

Abstract

Purpose

Overall, selection maps about the extent of the eutectic growth projects the solidification velocities leading to given microstructures. This is because of limitations of most of the set of results when obtained for single thermal gradients within the experimental spectrum. In these cases, associations only with the solidification velocity could give the false impression that reaching a given velocity would be enough to reproduce a result. However, that velocity must necessarily be accompanied by a specific thermal gradient during transient solidification. Therefore, the purpose of this paper is to not only project velocity but also include the gradients acting for each velocity.

Design/methodology/approach

Compilation of solidification velocity, v, thermal gradient, G, and cooling rate, Ṫ, data for Sn-Cu and Sn-Bi solder alloys of interest is presented. These data are placed in the form of coupled growth zones according to the correlated microstructures in the literature. In addition, results generated in this work for Sn-(0.5, 0.7, 2.0, 2.8)% Cu and Sn-(34, 52, 58)% Bi alloys solidified under non-stationary conditions are added.

Findings

When analyzing the cooling rate (Ṫ = G.v) and velocity separately, in or around the eutectic composition, a consensus cannot be reached on the resulting microstructure. The (v vs. G) + cooling rate diagrams allow comprehensive analyzes of the combined v and G effects on the subsequent microstructure of the Sn-Cu and Sn-Bi alloys.

Originality/value

The present paper is devoted to the establishment of (v vs. G) + cooling rate diagrams. These plots may allow comprehensive analyses of the combined v and G effects on the subsequent microstructure of the Sn-Cu and Sn-Bi alloys. This microstructure-processing mapping approach is promising to predict phase competition and resulting microstructures in soldering of Sn-Cu and Sn-Bi alloys. These two classes of alloys are of interest to the soldering industry, whereas manipulation of their microstructures is considered of utmost importance for the metallurgical quality of the product.

Details

Soldering & Surface Mount Technology, vol. 34 no. 1
Type: Research Article
ISSN: 0954-0911

Keywords

Article
Publication date: 15 June 2015

Sihong Liu, Zijian Wang, Yishu Wang, Liujiang Wang and Zhongzhi Fu

– The purpose of this paper is to propose a new yield function for granular materials based on microstructures.

Abstract

Purpose

The purpose of this paper is to propose a new yield function for granular materials based on microstructures.

Design/methodology/approach

A biaxial compression test on granular materials under different stress paths is numerically simulated by distinct element method. A microstructure parameter S that considers both the arrangement of granular particles and the inter-particle contact forces is proposed. The evolution of the microstructure parameter S under the simulated stress paths is analyzed, from which a yield function for granular materials is derived. The way of determining the two parameters involved in the yield function is proposed.

Findings

The new yield function is calibrated using the test data of one sand and two rockfill materials. The shape of the new yield surface is similar to that of the Cam-clay model.

Originality/value

The paper proposes a microstructure parameter S, which considers both the arrangement of granular particles and the inter-particle contact forces. From the evolution of S, a yield function for granular materials is derived. The proposed yield function has a simple structure and the parameters are easy to be determined, leading to a feasible realization of engineering application.

Details

Engineering Computations, vol. 32 no. 4
Type: Research Article
ISSN: 0264-4401

Keywords

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