Descripción del proyecto
THE OVERALL AIM OF THE PROJECT IS TO MAKE A SIGNIFICANT ADVANCE IN THE UNDERSTANDING OF EXTRINSIC SIZE EFFECTS IN THE PLASTIC DEFORMATION OF METALS (SAMPLE DIMENSIONS IN THE MICROMETER SCALE, INCLUDING MICRON SIZE VOIDS), A SYNERGETIC APPROACH WILL BE SOUGHT BETWEEN STATE-OF-THE-ART COMPUTATIONAL MULTI-SCALE MODELING (DISCRETE DISLOCATION DYNAMICS, DDD, AND STRAIN GRADIENT SINGLE CRYSTAL PLASTICITY MODELING, SGSCP) AND STATE-OF-THE-ART MECHANICAL TESTING AT THE MICROMETER AND NANOMETER SCALE, INCLUDING THE FABRICATION OF MICROSAMPLES BY FOCUSED ION BEAM (FIB) AND THE IN-SITU MECHANICAL TESTING IN THE SCANNING ELECTRON MICROSCOPE (SEM), TO THIS END, THIS COORDINATED PROJECT BRINGS TOGETHER TWO GROUPS WITH EXPERTISE IN THESE FIELDS: THE DEPARTMENT OF MATERIALS SCIENCE OF THE POLYTECHNIC UNIVERSITY OF MADRID (UPM) AND FOUNDATION IMDEA MATERIALS, UPM, THE PROJECT COORDINATOR, LEADS THE SUB-PROJECT ON SIMULATION, WHILE IMDEA-MATERIALS WILL LEAD THE SUB-PROJECT ON EXPERIMENTAL TESTING, HOWEVER, BOTH GROUPS WILL SUBSTANTIALLY CONTRIBUTE TO BOTH SUB-PROJECTS,FIRST, A THEORETICAL STUDY OF DIFFERENT SGSCP APPROACHES WILL BE MADE, THE ABILITY OF SGSCP MODELS TO REPRODUCE DDD RESULTS IN SEVERAL BENCHMARK PROBLEMS WILL BE ESTABLISHED AND MODIFICATIONS OF THE CURRENT SGSCP MODELS WILL BE INTRODUCED IN ORDER TO IMPROVE THEIR ABILITY TO REPRODUCE THE PHYSICAL PROCESSES OF PLASTIC DEFORMATION BY DISLOCATION GLIDE, FOLLOWING THE THEORETICAL STUDY, THREE FUNDAMENTAL PROCESSES WITH INHERENT SIZE EFFECTS WILL BE STUDIED IN DETAIL:(I)THE DEFORMATION OF SINGLE CRYSTAL MICRON SIZE -SAMPLES UNDER DIFFERENT STRESS CONDITIONSTHE AIM IS TO DEVELOP THE EXPERIMENTAL SET-UP NEEDED TO CARRY OUT MECHANICAL TESTS OF MICRON SIZE SPECIMENS INSIDE THE SEM UNDER DIFFERENT STRESS CONDITIONS AND TO ELUCIDATE THE PHYSICAL ORIGINS OF THE SPECIMEN SIZE EFFECTS OBSERVED WHEN THE SAMPLE DIMENSIONS ENTER THE MICROMETER REGIME, THE RESULTS OF THESE EXPERIMENTS WILL SERVE TO TEST THE ABILITY OF THE PROPOSED MODELS TO CAPTURE SIZE-EFFECTS AND TO SUPPLY QUANTITATIVE PHYSICALLY BASED PARAMETERS TO THESE MODELS,(II)THE PROCESS OF VOID GROWTH IN METALSTHE AIM IS TO DEVELOP AN UNDERSTANDING OF HOW THE ELEMENTARY PROCESSES OF PLASTIC DEFORMATION AND THEIR SIZE EFFECTS CONTRIBUTE TO THE PROCESS OF VOID GROWTH, THIS PROCESS HAS AN ENORMOUS PRACTICAL INTEREST BECAUSE OF ITS IMPLICATIONS FOR THE MICROMECHANISMS INVOLVED IN THE DUCTILE FAILURE OF METALS AND FOR THE DEVELOPMENT OF MORE ACCURATE PHYSICALLY BASED FRACTURE MODELS, (III)THE NANO-INDENTATION PROCESSINSTRUMENTED NANO-INDENTATION (INI) IS A PROCESS DURING WHICH THE SCALE LEVELS ARE CONTINUOUSLY COVERED: FROM THE PURE ELASTIC CONTACT TO THE DISLOCATION NUCLEATION AND TO THE DISLOCATION MULTIPLICATION IN THE PRESENCE OF STRONG STRAIN GRADIENTS, THE SPECIFIC OBJECTIVES OF THIS PART ARE THE EXPERIMENTAL OBSERVATION OF THE MICROMECHANISMS OF DEFORMATION AROUND NANO-INDENTATIONS AND THE SIMULATION OF THE NANO-INDENTATION PROCESS BASED ON A MULTISCALE MODELING APPROACH, INCLUDING DISCRETE DISLOCATION DYNAMIC MODELS AND ADVANCED CONTINUUM ELASTOPLASTICITY MODELING,THE FINAL MAIN RESULT OF THE PROJECT IS A COMPLETE CHARACTERIZATION OF THE MECHANICAL BEHAVIOR OF SINGLE CRYSTALS AT THE MICROMETER AND NANOMETER SCALE AS WELL AS THE MECHANISM OF VOID GROWTH INSIDE THEM, INCLUDING SIZE EFFECTS, THE SECOND MAIN RESULT IS THE IMPLEMENTATION OF TWO MODELS, PHYSICALLY BASED, TO SIMULATE THE PLASTIC BEHAVIOR OF METALS CONSIDERING SIZE EFFE PLASTICIDAD\EFECTOS TAMAÑO\CRECIMIENTO DE HUECOS\NANO-MECANICA\NANO-INDENTACION\EXPERIMENTACION IN-SITU\DINAMICA DE DISLOCACIONES DISCRETAS\PLASTICIDAD CRISTALINA\HACES DE IONES ENFOCADOS (FIB)\CORRELACION DIGITAL DE IMAGENES (DIC)