title: Temperature variations at nano-scale level in phase transformed nanocrystalline NiTi shape memory alloys adjacent to graphene layers.
abstract: The detection and control of the temperature variation at the nano-scale level of thermo-mechanical materials during a compression process have been challenging issues. In this paper, an empirical method is proposed to predict the temperature at the nano-scale level during the solid-state phase transition phenomenon in NiTi shape memory alloys. Isothermal data was used as a reference to determine the temperature change at different loading rates. The temperature of the phase transformed zone underneath the tip increased by ∼3 to 40 °C as the loading rate increased. The temperature approached a constant with further increase in indentation depth. A few layers of graphene were used to enhance the cooling process at different loading rates. Due to the presence of graphene layers the temperature beneath the tip decreased by a further ∼3 to 10 °C depending on the loading rate. Compared with highly polished NiTi, deeper indentation depths were also observed during the solid-state phase transition, especially at the rate dependent zones. Larger superelastic deformations confirmed that the latent heat transfer through the deposited graphene layers allowed a larger phase transition volume and, therefore, more stress relaxation and penetration depth.
authors.affiliation: Institute for Frontier Materials, Deakin University, Waurn Ponds, Geelong, VIC 3217, Australia. abbas.amini@deakin.edu.au
authors.forename: Abbas
authors.initials: A
authors.lastname: Amini
authors.forename: Chun
authors.initials: C
authors.lastname: Cheng
authors.forename: Minoo
authors.initials: M
authors.lastname: Naebe
authors.forename: Jeffrey S
authors.initials: JS
authors.lastname: Church
authors.forename: Nishar
authors.initials: N
authors.lastname: Hameed
authors.forename: Alireza
authors.initials: A
authors.lastname: Asgari
authors.forename: Frank
authors.initials: F
authors.lastname: Will
mesh_terms: D000497:Alloys / Q000737:chemistry*; D006108:Graphite / Q000737:chemistry*; D053758:Nanoparticles / Q000737:chemistry; D009532:Nickel / Q000737:chemistry*; D044367:Phase Transition; D013696:Temperature; D014025:Titanium / Q000737:chemistry
chemical_list: D000497:Alloys; D006108:Graphite; D009532:Nickel; D014025:Titanium