Pan American Materials Congress: Nanocrystalline and Ultra-fine Grain Materials and Bulk Metallic Glasses: Superplasticity, Wear, Corrosion, Magnetic, Electric and Functional Properties
Sponsored by: Third Pan American Materials Congress Organizing Committee
Program Organizers: Terence Langdon, University of Southern California; Megumi Kawasaki, Oregon State University; Roberto Figueiredo, Federal University of Minas Gerais; Jose-Maria Cabrera, Universidad Politecnica de Catalunya
Wednesday 3:40 PM
March 1, 2017
Room: Marina F
Location: Marriott Marquis Hotel
Session Chair: Roberto Figueiredo, Universidade Federal de Minas Gerais; Kaveh Edalati, Kyushu University
Achieving Superplasticity in a Bi-Sn Alloy Processed by Equal-channel Angular Pressing: Fariba Naghdi1; Roberto Figueiredo2; Terence Langdon3; 1University of Southampton; 2Universidade Federal de Minas Gerais; 3University of Southern California
A Bi‒42Sn eutectic alloy was processed by equal-channel angular pressing (ECAP) at room temperature using processing route A for 1, 2, 4 and 8 passes. Tensile testing was performed at room temperature under initial strain rates in the range of 10-5 - 10-2 s-1. All samples demonstrated increasing elongations to failure with decreasing strain rate. The largest elongation to failure of ~1300% was obtained in the sample processed by ECAP for 8 passes at an initial strain rate of 10-5 s-1. This was much improved by comparison with the as-cast Bi‒42Sn alloy
4:00 PM Cancelled
Formation of Ultrafine-Grained Structure in NiTi alloys by ECAP-“Conform”: Egor Prokofiev1; Ivan Lomakin1; Dmitry Gunderov2; Ruslan Valiev1; 1Saint Petersburg State University; 2Ufa State Aviation Technical University
The equal channel angular pressing (ECAP) technique allows to refine structure of bulk samples of NiTi-based alloys and significantly increase their strength and shape memory effect parameters. However, for practical applications continuous ECAP-"Conform" method is more promising technique. This approach allowing to receive a long-length semi-products such as rods. Present work shows possibility of ultrafine-grained (UFG) structure formation with a grain size of about 500 nm in NiTi alloys using ECAP-"Conform". The influence of ECAP-"Conform" processing on parameters of the microstructure, phase transformations and mechanical properties of NiTi alloy have been investigated. Results of comparative pseudoelastic cycling of the alloy NiTi in coarse-grained and UFG states are presented and discussed.
Evaluation of the Effect of Grain Refinement by Severe Plastic Deformation on Biocompatibility and Corrosion Rate of Pure Magnesium: Claudio Silva1; Ana Celeste Oliveira1; Cíntia Costa1; Roberto Figueiredo1; Maria de Fátima Leite1; Marivalda Magalhães1; Vanessa Lins1; Terence Langdon2; 1Federal University of Minas Gerais; 2University of Southampton
Magnesium has potential for use as a biodegradable material. The present paper evaluates the effect of processing by severe plastic deformation on the grain refinement, hardness evolution, biocompatibility and corrosion rate. Commercial purity magnesium was received as cast slabs and processed by rolling, equal-channel angular pressing and high-pressure torsion to produce samples with average grain sizes in the range 0.5 ~ 300 mm. Tetrazolium dye-based cytotoxicity test shows that severe plastic deformation does not affect the metabolic activity of osteoblastic cells. However, the corrosion rate is affected by the processing route.
Wear Resistance of an Ultrafine-grained Cu-Zr Alloy Processed by High-pressure Torsion: Jittraporn Wongsa-Ngam1; Jianwei Li2; Jie Xu2; Terence Langdon3; 1King Mongkut's Institute of Technology Ladkrabang; 2Harbin Institute of Technology; 3University of Southern California
In order to produce ultrafine grains, a copper alloy, Cu-0.1% Zr, was processed by high-pressure torsion (HPT) at room temperature. The wear properties were evaluated by using ball-on-disc dry sliding tests on both the as-received material and on the HPT-processed material. The tests were conducted with various normal loads and rotational speeds to examine the effect of loads and speed. The results show that the ultrafine-grained Cu-Zr alloy processed by HPT has a higher wear resistance than the as-received material due to the significant grain refinement.
Wear Resistance and Electroconductivity of Copper and CuCrZr Alloy Subjected to Severe Plastic Deformation: Alexander Zhilyaev1; Anna Morozova2; Jose Maria Cabrera3; Rustam Kaibyshev2; 1Fundació CTM Centre Tecnològic; 2Belgorod State University; 3Universitat Politècnica de Catalunya
The ultrafine-grained microstructures and functional properties (wear and electrical conductivity) of pure copper and the Cu- 0.3%Cr-0.5%Zr alloy subjected to severe plastic deformation were investigated. Severe plastic deformation led to a significant decrease of the wear resistance because of the rapid surface damage to both Cu and Cu-based alloy, where a high density of dislocations was arranged in stochastic low-angle subboundaries by brittle fracture. Further deformation by subsequent ECAP passes promoted the subdivision of the shear bands by the geometrically necessary boundaries. Correspondingly, the number of fine crystallites outlined by HABs increased, and the wear rate decreased.
High-Pressure Torsion of Ceramics with Functional Properties: Kaveh Edalati1; Hadi Razavi-Khosroshahi2; Masayoshi Fuji2; Zenji Horita1; 1Kyushu University; 2Nagoya Institute of Technology
Ceramics are considered as brittle materials at ambient temperature and can hardly be deformed. This study shows that plastic strain can be successfully imposed at room temperature on different ceramic materials such as Al2O3, ZrO2, TiO2, Y2O3, BaTiO3 and WC by application of high-pressure torsion (HPT) method. Several features are observed after HPT processing: formation of different kinds of lattice defects such as dislocations and oxygen vacancies, formation of nanograins, occurrence of phase transformations and improvement of functional properties for energy applications.
Nanostructured Al-Mg-Si Alloys for Electrical Conductors: Ilchat Sabirov1; Ruslan Valiev2; Georgiy Raab2; Alexandr Arutyunyan3; Maxim Murashkin2; 1IMDEA Materials Institute; 2Ufa State Aviation Technical University; 3Saint Petersburg State University
Mechanical strength and electrical conductivity are among the most important properties of conducting metallic materials used in electrical engineering. However, high electrical conductivity and high strength are usually mutually exclusive due to physical nature of these properties. The approach of intelligent nanostructural design in the Al-Mg-Si alloys has enabled to increase the material strength with no degradation of its electrical conductivity, or even its simultaneous improvement. Moreover, nanostructuring of the Al-Mg-Si alloys can further increase their in-use properties. This work aims to overview the relationship between the microstructure and properties, which are important for application of the nanostructured Al-Mg-Si wires for overhead power lines, such as mechanical strength, ductility, electrical conductivity and fatigue resistance.