TY - JOUR
T1 - Effect of thermal cycling on multistage martensitic transformation in aged ti-50.8 at% ni alloy
AU - Ravari, Banafsheh Karbakhsh
AU - Mitsuhara, Masatoshi
AU - Farjami, Sahar
AU - Nishida, Minoru
PY - 2013
Y1 - 2013
N2 - The effect of thermal cycling on multistage martensitic transformation (MMT) in aged Ti-50.8 at% Ni alloy was investigated. The specimens were solution-treated at 1273 K for 3.6 ks and then aged at 773 K for 3.6 ks in vacuum without atmosphere regulation. Upon cooling the aged specimens clearly showed quadruple-stage transformation denoted as B2 → R → M1 → M2 → M3. The peak temperatures of exothermic reactions R M1 and M2(corresponding to the R-phase M1 and M2 transformations respectively) in the differential scanning calorimetry (DSC) cooling curve were rather stable up to 100 thermal cycles since there were fine Ti3Ni4 precipitates with high distribution density in the intermediate and grain boundary regions. These precipitates prevented the formation of dislocations during thermal cycling. On the other hand the peak temperature of exothermic reaction M3 (corresponding to the M3 transformation) drastically decreased with increasing the number of thermal cycles since there were large Ti 3Ni4 precipitates with low distribution density. Many dislocations were observed in the central regions of grains after 100 thermal cycles.
AB - The effect of thermal cycling on multistage martensitic transformation (MMT) in aged Ti-50.8 at% Ni alloy was investigated. The specimens were solution-treated at 1273 K for 3.6 ks and then aged at 773 K for 3.6 ks in vacuum without atmosphere regulation. Upon cooling the aged specimens clearly showed quadruple-stage transformation denoted as B2 → R → M1 → M2 → M3. The peak temperatures of exothermic reactions R M1 and M2(corresponding to the R-phase M1 and M2 transformations respectively) in the differential scanning calorimetry (DSC) cooling curve were rather stable up to 100 thermal cycles since there were fine Ti3Ni4 precipitates with high distribution density in the intermediate and grain boundary regions. These precipitates prevented the formation of dislocations during thermal cycling. On the other hand the peak temperature of exothermic reaction M3 (corresponding to the M3 transformation) drastically decreased with increasing the number of thermal cycles since there were large Ti 3Ni4 precipitates with low distribution density. Many dislocations were observed in the central regions of grains after 100 thermal cycles.
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U2 - 10.2320/matertrans.M2013309
DO - 10.2320/matertrans.M2013309
M3 - Article
AN - SCOPUS:84890944139
VL - 54
SP - 2185
EP - 2188
JO - Materials Transactions
JF - Materials Transactions
SN - 0916-1821
IS - 12
ER -