1. Fatigue and Aeronautical Materials Research Group, Department of Materials and TechnologyUNESP ‐ São Paulo State University, 12516‐410 Guaratinguetá São Paulo Brazil
2. Materials Science and Engineering Graduate Program (PGMAT)University of Caxias do Sul (UCS) 95070‐490 Caxias do Sul Rio Grande do Sul Brazil
3. Positron Annhilation Spectroscopy Laboratory (LEAP)Federal University of Minas Gerais (UFMG) 31270‐901 Belo Horizonte Minas Gerais Brazil