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Lightweight Materials Spotlighted in February JOM |
Posted on: 1/18/2013 12:00:00 AM... February’s exceptionally robust issue of JOM explores the technical theme of Lightweight Materials within three topics: Composite Materials: Modeling and Simulation; Aluminum Processing; and Advances in Refractory Metals and Alloys.COMPOSITE MATERIALS: MODELING AND SIMULATION
In addition, be sure to check out “Contribution of Electricity to Materials Processing: Historical and Current Perspectives” by Antoine Allanore, who originally presented the material as the co-recipient of the 2012 Vittorio de Nora Prize for Environmental Improvements in Metallurgical Industries. Another feature, “Faces of the Future,” looks at the progress and expansion of the TMS Early Career Faculty Fellow program, while this month’s “News and Update” section highlights the TMS society and division award winners who will be honored during the TMS 2013 Annual Meeting and Exhibition, March 3-7, in San Antonio, Texas.
The entire February 2013 issue of JOM is now available online. An overview of the technical topics and articles is presented below. As TMS’s publishing partner, Springer, transitions to a new online format, TMS members will need to access JOM by logging in to the JOMGateway.net, using their TMS Username and Password. Through this site, TMS members can also access their online subscriptions to Journal of Electronic Materials, Metallurgical and Materials Transactions A and B, and Integrating Materials and Manufacturing Innovation.
Modeling and Simulation in Composite Materials: Integration from Nanostructure to Component-Level Design
The commentary introduces the technical topic and summarizes the papers that comprise it. Notes the author, “The rapid growth in the usage of composite materials has made it necessary to summarize the progress made in the modeling and simulation fields, and thus determine future perspectives.”
Effect of Curing and Functionalization on the Interface Thermal Conductance in Carbon Nanotube–Epoxy Composites
Vikas Varshney, Ajit K. Roy, Tyler J. Michalak, Jonghoon Lee, and Barry L. Farmer
This study investigates the interface thermal conductance in a functionalized carbon nanotube (CNT)–epoxy composite system and how it is modified when the surrounding matrix is cured. Results suggest that the interface conductance can be strongly influenced by the thermal properties of the bulk matrix, as well as the interface chemistry of the additives such as CNTs.
Simulation of Fracture Nucleation in Cross-Linked Polymer Networks
J.C. Moller, S.A. Barr, E.J. Schultz, T.D. Breitzman, and R.J. Berry
The authors describe a novel atomistic simulation method in which polymer systems can be deformed in strain-rate-controlled deformation while bond scission is enabled. The aim of the study is to provide insight into the nanoscale origins of fracture. This method and its results could potentially become part of a solution system that spans multiple length and time scales and that could more completely represent such mechanical events as fracture.
Formation of Nanotubes and Nanocoils by Spontaneous Self-Rolling of Aluminum (001)/(111) Bilayer
Jijun Lao and Dorel Moldovan
This article introduces a novel nanomechanical architecture to form pure metallic nanotubes or nanocoils via spontaneous self-rolling of initial planar free-standing bilayer thin films.
Molecular Dynamics Simulation of FCC Metallic Nanowires: A Review
Jijun Lao, Mehdi Naghdi Tam, Dinesh Pinisetty, and Nikhil Gupta
Molecular dynamic simulation studies are reviewed to understand the influence of strain rate, temperature, and cross-section size on the mechanical properties of face-centered cubic (FCC) metallic nanowires (MNWs).
Shock Waves Impacting Composite Material Plates: The Mutual Interaction
High-performance, fiber-reinforced polymer composites have been extensively used in structural applications in the last 30 years because of their light weight, combined with high specific stiffness and strength at a rather low cost. However, the mechanical response and characterization of such materials under transient dynamic loading caused with shock impact induced by blast is not well understood. This paper provides a physics-based analysis of the phenomena involved and a critical review of existing computational techniques, along with some recent results involving face-on impact of shock waves on thin composite plates.
Multi-resolution Modeling of the Dynamic Loading of Metal Matrix Composites
Rémi Dingreville, Joshua Robbins, and Thomas Voth
The mechanical behavior of metal matrix composites (MMCs) varies significantly under rapid straining as compared to quasi-static loading and is often dominated by underlying microstructural features (grain structure, porosity, inclusions, and defects). Analysis of the behavior of MMCs under dynamic loading requires theoretical and experimental approaches that integrate the strain rate and microstructural effects. This article introduces a multiresolution modeling capability for studying nonlinear planar wave propagation in heterogeneous materials with an application to MMCs.
Multiscale Modeling of Composites: Toward Virtual Testing . . . and Beyond
J. Llorca, C. González, J.M. Molina-Aldareguía, and C.S. Lópes
This paper presents recent developments in the area of multiscale modeling of fiber-reinforced polymers and outlines a roadmap for extending the strategy described to include functional properties and processing into the simulation scheme.
Extracting Constitutive Stress–Strain Behavior of Microscopic Phases by Micropillar
J.J. Williams, J.L. Walters, M.Y. Wang, N. Chawla, and A. Rohatgi
In this study, micropillar compression was employed to determine the mechanical properties of individual microconstituents in metallic materials with "composite" microstructures, consisting of two distinct microconstituents: (a) a Mg-Al alloy with pure Mg dendrites and eutectic regions and (b) a powder metallurgy steel with ferrite and martensite constituents.
A Review of Thermal Conductivity of Polymer Matrix Syntactic Foams—Effect of Hollow Particle Wall Thickness and Volume Fraction
Nikhil Gupta and Dinesh Pinisetty
Hollow-particle-filled composites called syntactic foams are lightweight particulate composites that are useful in weight-sensitive applications such as aerospace and marine structures. This review article summarizes the available experimental results and theoretical models related to the thermal conductivity of syntactic foams. Experimental results are available for only a few compositions of syntactic foams. Four theoretical models are tested with the experimental data and found to provide close predictions. These models are used to conduct parametric studies. It is observed that the thermal conductivity of syntactic foams decreases as the volume fraction of thin-walled particles is increased. An inverse relationship is observed for thick-walled, hollow-particle-filled syntactic foams. These models can help in designing syntactic foams with required thermal conductivity.
Modeling Damage Growth in Oxidized High-Temperature Polymeric Composites
Nan An and Kishore Pochiraju
Thermal oxidation is a major degradation mechanism for polymers and composites operating at high temperatures. Controlling the damage progression in oxidative environments is critical for enhancing the long-term durability of these materials. In this article, three-dimensional, finite-element methods are used to simulate both oxidation layer and damage growth in polymers subjected to bending loads and laminated composites subjected to uniaxial tension.
Computational Modeling of Piezoelectric Foams
K.S. Challagulla and T.A. Venkatesh
Piezoelectric materials, by virtue of their unique electromechanical characteristics, have been recognized for their potential utility in many applications as sensors and actuators. However, the sensing or actuating functionality of monolithic piezoelectric materials is generally limited. This article captures key results from the recent developments in the field of computational modeling of novel piezoelectric foam structures. It is demonstrated that the fundamental elastic, dielectric, and piezoelectric properties of piezoelectric foam are strongly dependent on the internal structure of the foams and the material volume fraction.
A New Energy-Efficient and Environmentally Friendly Process to Produce Aluminum
The Hall-Heroult process to produce aluminum is more than 125 years old. Larger, more efficient cells have been developed, and process control has improved, but the process is basically unchanged. A new process has been under development since 1990 that promises 20 percent lower capital cost and 20 percent lower operating cost and no CO2 or fluorocarbon emissions. A new cell design, new anode and cathode materials, new electrolyte, and new operating conditions are based on experience over the past six decades. The evolution of this technology to its present state is described here.
Optimization of Al Matrix Reinforced with B4C Particles
Mohsen Ostad Shabani and Ali Mazahery
In the current study, abrasive wear resistance and mechanical properties of A356 composite reinforced with B4C particulates were investigated. A center particle swarm optimization algorithm (CenterPSO) is proposed to predict the optimal process conditions in fabrication of aluminum matrix composites.
Preparation and Characteristics of Al Matrix Composites Reinforced with ZnWO4 Coated (WO3p +ABOw) Hybrid Reinforcements
Y.C. Feng, G.J. Cao, G.H. Fan, L.P. Wang, and L. Geng
In this article, the ZnWO4 coating was prepared successfully on the surfaces of WO3 particulates and Al18B4O33 whiskers by a chemical precipitation method. An Al matrix composite with coated reinforcements was then fabricated by a squeeze casting technique. Mechanical property testing shows that the ultimate tensile strength, elastic modulus, and elongation of the hybrid composites with coated reinforcements are improved greatly by introduction of ZnWO4 coating.
The Nondestructive Determination of the Aluminum Content in Pressed Skulls of Aluminum Dross
Varuzan Kevorkijan, Sreco Davor Škapin, and Uroš Kovacec
During production of primary and secondary aluminum, various amounts (in some cases up to 200 kg) of aluminum dross, a mixture consisting of molten aluminum metal and different oxide compounds (the nonmetallic phase), is skimmed per tonne of molten metal. To preserve the maximum aluminum content in hot dross for further extraction, it is necessary to cool the dross immediately after skimming. One way to do this is to press the skimmed hot dross in a press. In this process, the skimmed dross is transformed into so-called pressed skulls, with characteristic geometry convenient for storage, transport, or further in-house processing. In the model developed in this work, the aluminum content in pressed skulls was expressed as a function of the pressed skulls density, the density of the nonmetallic phase, and the volume fraction of closed pores. In addition, the model demonstrated that, under precisely defined conditions (i.e., skulls from the dross of the same aluminum alloy and skimmed, transported, cooled, and pressed in the same way and under the same processing conditions), when other parameters except the pressed skulls density remain constant, the aluminum content in pressed skulls can be expressed as a linear function of the pressed skulls density. Following the theoretical considerations presented in this work, a practical industrial methodology was developed for nondestructive prediction of the amount of free aluminum in pressed skulls.
Characterization of Mechanical Properties of Aluminum Processed by Repetitive Corrugation and Straightening Process using Taguchi Analysis
H.S. Siddesha and M. Shantharaja
The severe plastic deformation process is capable of developing the submicron grain structures in metallic alloys and to improve the mechanical properties. In this work, an attempt has been made to study the influence of RCS parameters like strain rate, number of passes, and plate thickness to produce grain refinement in metallic alloys.
ADVANCES IN REFRACTORY METALS AND ALLOYS
Recent Development in Alloying Designs and Computational Modeling in Refractory Metals
This commentary highlights the papers related to the Advances in Refractory Metals and Alloys technical topic.
Effects of Zr Additions on the Microstructure and the Mechanical Behavior of PM
M. Krüger, D. Schliephake, P. Jain, K.S. Kumar, G. Schumacher, and M. Heilmaier
In this article, current understanding on the effects of Zr additions on the properties of three-phase Mo-Si-B alloys is reported. This novel group of materials, with high melting points around 2000°C, have been identified as potential alloy systems for structural applications at temperatures beyond 1200°C, potentially substituting or supplementing state-of-the-art nickel-base superalloys in the power generation industry.
Extended Functionality of Environmentally Resistant Mo-Si-B-Based Coatings
J.H. Perepezko and Ridwan Sakijda
Multiphase Mo-Si-B alloys with compositions, which yield the ternary intermetallic Mo5SiB2 (T2) phase as a key microstructure constituent together with the Mo and Mo3Si phases, offer an attractive balance of high melting temperature, oxidation resistance, and mechanical properties. The investigation of reaction kinetics involving the T2 phase enables the analysis of oxidation in terms of diffusion pathways and the design of effective coatings.
Novel Highly Porous Metal Technology in Artificial Hip and Knee Replacement: Processing Methodologies and Clinical Applications
John Muth, Matthew Poggie, Gene Kulesha, and R. Michael Meneghini
Hip and knee replacement can dramatically improve a patient’s quality of life through pain relief and restored function. Fixation of hip and knee replacement implants to bone is critical to the success of the procedure. A variety of roughened surfaces and three-dimensional porous surfaces has been used to enhance biological fixation on orthopedic implants. Recently, highly porous metals have emerged as versatile biomaterials that may enhance fixation to bone and are suitable to a number of applications in hip and knee replacement surgery. This article provides an overview of several processes used to create these implant surfaces.
First-Principles Calculation of Nb2AlC/Nb Interfaces
Liuxi Tan and Shizhong Yang
The authors describe a first-principles density functional theory method and molecular dynamics simulation on the Nb2AlC(001)/Nb(001), Nb2AlC(001)/Nb(110), and Nb2AlC(001)/Nb(111) interfaces. The results show that the Nb2AlC(001)/Nb(111) interface structure is the most stable structure of the three. The stable Nb2AlC(001)/Nb(111) structure may have very good oxidation resistance for applications in high-temperature turbines.
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