Grain ejection associated with thermocycling of Cu-Al-Ni shape memory alloy

•A recently discovered phenomenon of grain ejection is for the first time explained.•In CuAlNi alloy, the first ejected grain was observed after 400 load-free thermocycles.•After 500 thermocycles, an average of 8 grain was ejected per square centimeter.•Surface grain ejection was a consequence of in...

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Bibliographic Details
Published in:Materials letters 2018-01, Vol.210, p.54-57
Main Authors: Pereira, Elaine Cristina, Mathlakova, Lioudmila Aleksandrovna, da Silva Figueiredo, André Ben-Hur, Lima, Eduardo Sousa, dos Santos Paula, Andersan, Monteiro, Sergio Neves
Format: Article
Language:English
Subjects:
Alloys
Aluminum base alloys
Copper base alloys
Cu-Al-Ni alloy
Ejection
Fracture mechanics
Grain boundaries
Grain ejection
Image processing
Intergranular fracture
Martensite
Martensitic stainless steel
Martensitic transformation
Martensitic transformations
Materials science
Nickel base alloys
Shape memory alloys
Shape memory materials
Thermal cycling
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Summary:•A recently discovered phenomenon of grain ejection is for the first time explained.•In CuAlNi alloy, the first ejected grain was observed after 400 load-free thermocycles.•After 500 thermocycles, an average of 8 grain was ejected per square centimeter.•Surface grain ejection was a consequence of intergranular fracture.•Martensite transformation related to thermocycles causes grain boundary separation. The phenomenon of metallic grain ejection is for the first time explained. An evaluation of ejected grains was performed in Cu-Al-Ni shape memory alloy load-free cycled up to 500 times within the temperature interval of reversible martensitic transformation (RMT). An intergranular fracture mechanism related to RMT is proposed to this phenomenon. By image processing, 8grains/cm2 after 500 cycles were measured. This is attributed to γ′1 martensite transformation at the grain boundaries.
ISSN:0167-577X
1873-4979
DOI:10.1016/j.matlet.2017.08.123