In-situ TEM of stress induced martensitic transformation in Ni-Ti microwires

Date: 5 April 2019

Venue: Campus Groenenborger, U.408 - Groenenborgerlaan 171 - 2020 Antwerpen (route: UAntwerpen, Campus Groenenborger)

Time: 11:30 AM - 12:30 PM

Organization / co-organization: emat

Short description: EMAT friday lecture by Saeid Pourbabak

Near equiatomic Ni-Ti alloys with appropriate heat treatment exhibit shape memory and superelastic properties originating from the underlying martensitic transformation. Although stress induced martensitic transformations have been well studied and utilized at macroscale, not many investigations have been performed at the nanoscale, partly due to technical restrictions. Such studies are, however, essential in order to apply Ni-Ti in small-scale devices.

Combination of TEM and mechanical tests has been performed on some submicron single grain and polycrystalline NiTi samples. While performing mechanical tests, mechanical data was collected by the holder and TEM videos are recorded showing the various stages of the martensitic transformation. Mechanical characteristics of the submicron samples, such as height of the plateau, Young's modulus, the strain at which the martensitic transformation starts, etc. are compared for samples with different thicknesses and textures as well as the macrosize sample.