Microstructure of martensitic phase in the Co39Ni33Al28 shape memory alloys revealed by transmission electron microscopy

In the Co39Ni33Al28 alloy, the ferromagnetic shape memory effect was investigated. A martensitic transformation (MT) occurred in the Co39Ni33Al28 alloy when the temperature was lower than the martensitic start transformation temperature, MS = 233 K. The morphologies and microstructures of the martensitic phase characterized by transmission electron microscope (TEM) showed a new 28-layered (28M) modulated martensite consisting of pinstripes and co-existing with the non-modulated martensite. Anomalies in magnetic properties and strain emerging around the MT have been briefly discussed.