TY - JOUR
T1 - Thermally induced fcc - hcp martenistic transformation in Co-Ni
AU - Liu, Yinong
AU - Yang, Hong
AU - Liu, Yan
AU - Jiang, B.
AU - Ding, J.
AU - Woodward, Rob
PY - 2005
Y1 - 2005
N2 - This study investigated the thermal behaviour of the fcc ↔ hcp martensitic transformation of Co–Ni alloys. The transformation was found to be incomplete in both directions upon cooling and heating. Upon thermal cycling, the transformation, as detected by differential scanning calorimetry, diminished rapidly, indicating that the transformation was highly irreversible. Optical microscopic observation revealed that surface reliefs appeared on pre-polished surfaces upon forward transformation, but did not disappear upon the reverse transformation, implying that the transformation also exhibited mechanical irreversibility. The irreversibility is explained on the basis of multiple choice of crystalline shuffling along for the fcc ↔ hcp transformation. These observations suggest that the fcc ↔ hcp martensitic transformation system in Co–Ni is not suitable for thermomechanical shape memory effect, which requires high reversibility of the transformation both crystallographically and mechanically. It is regarded that this rule is generic and applicable to other fcc ↔ hcp transformation systems.
AB - This study investigated the thermal behaviour of the fcc ↔ hcp martensitic transformation of Co–Ni alloys. The transformation was found to be incomplete in both directions upon cooling and heating. Upon thermal cycling, the transformation, as detected by differential scanning calorimetry, diminished rapidly, indicating that the transformation was highly irreversible. Optical microscopic observation revealed that surface reliefs appeared on pre-polished surfaces upon forward transformation, but did not disappear upon the reverse transformation, implying that the transformation also exhibited mechanical irreversibility. The irreversibility is explained on the basis of multiple choice of crystalline shuffling along for the fcc ↔ hcp transformation. These observations suggest that the fcc ↔ hcp martensitic transformation system in Co–Ni is not suitable for thermomechanical shape memory effect, which requires high reversibility of the transformation both crystallographically and mechanically. It is regarded that this rule is generic and applicable to other fcc ↔ hcp transformation systems.
U2 - 10.1016/j.actamat.2005.04.019
DO - 10.1016/j.actamat.2005.04.019
M3 - Article
VL - 53
SP - 3625
EP - 3634
JO - Acta Materialia
JF - Acta Materialia
SN - 1359-6454
IS - 13
ER -