Copyright © 2012 Joseph K. L. Lai et al. This is an open access article distributed under the Creative Commons Attribution
License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.This article has been made available through the Brunel Open Access Publishing Fund.This article is made available through the Brunel Open Access Publishing Fund

Chen, Z

Lai, JKL

Lo, KH

Ralph, B

Advances in Materials Science and Engineering

English

Joseph K. L. Lai

Brian Ralph

Zhiwen Chen

Kin Ho Lo

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Microstructural Evolution in Materials during Thermal Processing

Brunel University Research Archive

Hindawi Publishing CorporationAdvances in Materials Science and EngineeringVolume 2012, Article ID 302478, 2 pagesdoi:10.1155/2012/302478EditorialMicrostructural Evolution in Materials duringThermal ProcessingJoseph K. L. Lai,1 Brian Ralph,2 Zhiwen Chen,3 and Kin Ho Lo41Department of Physics and Materials Science, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong2Brunel University, Kingston Lane, Uxbridge, UB8 3PH, UK3School of Environmental and Chemical Engineering, Shanghai University, Shangda Road 99, P.O. Box 144, Shanghai 200444, China4Department of Electromechanical Engineering, University of Macau, Avenida Padre Toma´s Pereira, Taipa, Macau, ChinaCorrespondence should be addressed to Joseph K. L. Lai, apjoelai@cityu.edu.hkReceived 16 October 2011; Accepted 16 October 2011Copyright © 2012 Joseph K. L. Lai et al. This is an open access article distributed under the Creative Commons AttributionLicense, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properlycited.The study of materials science is mainly based on ourunderstanding of the relationship between microstructureand materials properties. Factors such as temperature, stress,and environment can lead to microstructural evolution witha concomitant change in properties. It is the materialsscientist’s role to harness our knowledge on this relationshipto produce materials with improved properties, or to predictthe performance of existing materials under various serviceconditions.Over the past two decades, there have been a burgeoningnumber of novel or improved materials. This developmentis accompanied by significant advances in techniques inmaterials characterization as well as increased sophisticationin theoretical methods for the analysis of microstructures.The application of these new techniques and methodologiesto study the microstructural evolution of novel materialsoﬀers tremendous opportunities for scientific advancementonmany fronts, with the prospect of providing new solutionsto problems which have hitherto remained intractable.The papers published in this special issue encompassvarious materials systems: metals and alloys, glass ceramics,thin films, nanowire, and oxide powders for engineeringapplications.The paper by Dehmas et al. reports an investigation onthe precipitate phases in Inconel 718, an important alloy forhigh temperature applications such as turbine blades. Usingtransmission electron microscopy and X-ray diﬀraction, theauthors were able to confirm the presence of rotation-ordered domains in δ plates and explain unexpected contrastby double diﬀraction due to overlapping phases.The paper by Ukai et al. is also focused on Nickel-basedsuper-alloy for high temperature turbine applications. Thisstudy has enhanced our understanding of the precipitationand growth kinetics of γ′ and its characteristics in mechani-cally alloyed materials.The paper by Hiraoka et al. reports the results of aninvestigation on the strength and ductility of tungsten sheetsafter various recrystallization treatments. Three-point bendtests were performed at temperatures between 290 and500K. Fracture surfaces were examined by scanning electronmicroscopy. The mechanical properties of tungsten andmolybdenum were compared.A glass ceramic material was studied by Montedo etal. in the their paper. The material studied is a candidatematerial for applications such as laminated tapes for screen-printed electronic components. The crystallization kineticswas studied using diﬀerential thermal analysis and scanningelectron microscopy.Other two papers were written by the same team ofauthors. Two titanium oxide glass ceramic materials withLa2O3 addition, one strontium rich and one lead rich, werestudied. The crystallization behavior of these materials wasinvestigated using diﬀerential thermal analysis and X-raydiﬀraction.Microstructural evolution during rapid thermal anneal-ing of Ge nanowires was investigated by Tang et al.in the seventh paper. Scanning electron microscopy andtransmission electron microscopy were used to observeNi2Ge/Ge/Ni2Ge nanowire heterostructures. This work has2 Advances in Materials Science and Engineeringimportant implications for the future development of fieldeﬀect transistors.Wang et al. present their work on zinc oxide thin filmsin the their paper. Two types of thin films were investigated:Ag ion-exchanged soda-lime glasses and aluminium-dopedZnO (AZO). Changes in chemical states and structuralmodification during and after heat treatment were explored.The results provide the basic information for determiningthe optimum heat treatment to grow silver quantum dots ofvarious size and density in thin films.Another interesting contribution on the subject of ZnOthin films appears in one of the papers. Japanese researchersfrom the Kochi University of Technology have developed anew technique for measuring the Youngs modulus of ultra-thin films with thickness in the range of about 10 nm. Thetechnique was applied to study the mechanical properties ofGa-doped ZnO thin films, a possible substitute material forindium-tin-oxide transparent electrodes.Another paper deals with powder materials for Lithiumion battery applications. Akao et al. from the Universityof Fukui produced LiNi0.5Mn1.5O4 cathode materials byflame combustion using a spray pyrolysis apparatus. X-ray diﬀraction revealed that, after calcination at 900◦C,crystalline powders with polygonal morphology and narrowparticle size distribution were obtained.The paper by Sola et al. is concerned with a literally“down to earth” problem. For many years, scientists havebeen developing ways to make use of fly ash in order to turnit from an industrial waste with environmental and storageproblems into a useful material. The most obvious solutionto this conundrum is to use it as an additive in sinteredbriquettes in the construction industry. These authors havedetermined the eﬀect of diﬀerent types of fly ash on thecompressive strength of sintered briquettes. They showedthat sintered briquettes samples made with Tuncbilek flyash had higher percentage of glassy phase and compressivestrength.Papers published in this special issue will be of interest tomaterials scientists and engineers who wish to extend theirknowledge on the eﬀect of thermal processing on a broadrange of materials. We would like to take this opportunityto thank all the authors who have submitted their papers tothis publication.Joseph K. L. LaiBrian RalphZhiwen ChenKin Ho Lo

Microstructural evolution in materials during thermal processing

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Hindawi Publishing CorporationAdvances in Materials Science and EngineeringVolume 2012, Article ID 302478, 2 pagesdoi:10.1155/2012/302478EditorialMicrostructural Evolution in Materials duringThermal ProcessingJoseph K. L. Lai,1 Brian Ralph,2 Zhiwen Chen,3 and Kin Ho Lo41Department of Physics and Materials Science, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong2Brunel University, Kingston Lane, Uxbridge, UB8 3PH, UK3School of Environmental and Chemical Engineering, Shanghai University, Shangda Road 99, P.O. Box 144, Shanghai 200444, China4Department of Electromechanical Engineering, University of Macau, Avenida Padre Toma´s Pereira, Taipa, Macau, ChinaCorrespondence should be addressed to Joseph K. L. Lai, apjoelai@cityu.edu.hkReceived 16 October 2011; Accepted 16 October 2011Copyright © 2012 Joseph K. L. Lai et al. This is an open access article distributed under the Creative Commons AttributionLicense, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properlycited.The study of materials science is mainly based on ourunderstanding of the relationship between microstructureand materials properties. Factors such as temperature, stress,and environment can lead to microstructural evolution witha concomitant change in properties. It is the materialsscientist’s role to harness our knowledge on this relationshipto produce materials with improved properties, or to predictthe performance of existing materials under various serviceconditions.Over the past two decades, there have been a burgeoningnumber of novel or improved materials. This developmentis accompanied by significant advances in techniques inmaterials characterization as well as increased sophisticationin theoretical methods for the analysis of microstructures.The application of these new techniques and methodologiesto study the microstructural evolution of novel materialsoﬀers tremendous opportunities for scientific advancementonmany fronts, with the prospect of providing new solutionsto problems which have hitherto remained intractable.The papers published in this special issue encompassvarious materials systems: metals and alloys, glass ceramics,thin films, nanowire, and oxide powders for engineeringapplications.The paper by Dehmas et al. reports an investigation onthe precipitate phases in Inconel 718, an important alloy forhigh temperature applications such as turbine blades. Usingtransmission electron microscopy and X-ray diﬀraction, theauthors were able to confirm the presence of rotation-ordered domains in δ plates and explain unexpected contrastby double diﬀraction due to overlapping phases.The paper by Ukai et al. is also focused on Nickel-basedsuper-alloy for high temperature turbine applications. Thisstudy has enhanced our understanding of the precipitationand growth kinetics of γ′ and its characteristics in mechani-cally alloyed materials.The paper by Hiraoka et al. reports the results of aninvestigation on the strength and ductility of tungsten sheetsafter various recrystallization treatments. Three-point bendtests were performed at temperatures between 290 and500K. Fracture surfaces were examined by scanning electronmicroscopy. The mechanical properties of tungsten andmolybdenum were compared.A glass ceramic material was studied by Montedo etal. in the their paper. The material studied is a candidatematerial for applications such as laminated tapes for screen-printed electronic components. The crystallization kineticswas studied using diﬀerential thermal analysis and scanningelectron microscopy.Other two papers were written by the same team ofauthors. Two titanium oxide glass ceramic materials withLa2O3 addition, one strontium rich and one lead rich, werestudied. The crystallization behavior of these materials wasinvestigated using diﬀerential thermal analysis and X-raydiﬀraction.Microstructural evolution during rapid thermal anneal-ing of Ge nanowires was investigated by Tang et al.in the seventh paper. Scanning electron microscopy andtransmission electron microscopy were used to observeNi2Ge/Ge/Ni2Ge nanowire heterostructures. This work has2 Advances in Materials Science and Engineeringimportant implications for the future development of fieldeﬀect transistors.Wang et al. present their work on zinc oxide thin filmsin the their paper. Two types of thin films were investigated:Ag ion-exchanged soda-lime glasses and aluminium-dopedZnO (AZO). Changes in chemical states and structuralmodification during and after heat treatment were explored.The results provide the basic information for determiningthe optimum heat treatment to grow silver quantum dots ofvarious size and density in thin films.Another interesting contribution on the subject of ZnOthin films appears in one of the papers. Japanese researchersfrom the Kochi University of Technology have developed anew technique for measuring the Youngs modulus of ultra-thin films with thickness in the range of about 10 nm. Thetechnique was applied to study the mechanical properties ofGa-doped ZnO thin films, a possible substitute material forindium-tin-oxide transparent electrodes.Another paper deals with powder materials for Lithiumion battery applications. Akao et al. from the Universityof Fukui produced LiNi0.5Mn1.5O4 cathode materials byflame combustion using a spray pyrolysis apparatus. X-ray diﬀraction revealed that, after calcination at 900◦C,crystalline powders with polygonal morphology and narrowparticle size distribution were obtained.The paper by Sola et al. is concerned with a literally“down to earth” problem. For many years, scientists havebeen developing ways to make use of fly ash in order to turnit from an industrial waste with environmental and storageproblems into a useful material. The most obvious solutionto this conundrum is to use it as an additive in sinteredbriquettes in the construction industry. These authors havedetermined the eﬀect of diﬀerent types of fly ash on thecompressive strength of sintered briquettes. They showedthat sintered briquettes samples made with Tuncbilek flyash had higher percentage of glassy phase and compressivestrength.Papers published in this special issue will be of interest tomaterials scientists and engineers who wish to extend theirknowledge on the eﬀect of thermal processing on a broadrange of materials. We would like to take this opportunityto thank all the authors who have submitted their papers tothis publication.Joseph K. L. 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Microstructural evolution in materials during thermal processing

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