Heat treatments and thermomechanical cycling influences on the R-phase in Ti-Ni shape memory alloys
AUTOR(ES)
Gonzalez, Cezar Henrique, Oliveira, Carlos Augusto do Nascimento, Pina, Euclides Apolinário Cabral de, Urtiga Filho, Severino Leopoldino, Araújo Filho, Oscar Olimpio de, Araújo, Carlos José de
FONTE
Materials Research
DATA DE PUBLICAÇÃO
2010-09
RESUMO
This article studies changes observed on the R-phase thermoelastic behavior in a near-equiatomic Ti-Ni shape memory alloy. Three kinds of procedures have been performed: different treatments, thermomechanical cycling under constant loading in shape memory helical springs and thermal cycling in as-treated and trained samples. Several heat treatments were carried out to investigate evolution of the R-phase by differential scanning calorimetry (DSC). A heat treatment was chosen on which R-phase is absent. Shape memory springs were produced and submitted to a training process in an apparatus by tensioning the springs under constant loading. Thermal cycling in DSC was realized in as-treated and trained samples. Several aspects of one-step (B2→B19') and two-steps (B2→R→B19') martensitic transformations and R-phase formation and their evolution during tests were observed and discussed.
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