Pak. J. Engg. Appl. Sci. Vol. 29 July, 2021 (p. 81-89) 81 DSC-investigation of ultra thin sheet of NiTi Shape Memory Alloy Farwa Shaukat 1 , Muhammad Arshad Javid 1 , Muhammad Irfan 1 , M.Saifullah. Awan 2 1. Department of Basic Sciences and Humanities, University of Engineering and Technology Taxila.47050 2. Nanoscience and Technology Department, National Center for Physics Islamabad, Pakistan  Corresponding Author: Email: sssawan@gmail.com Abstract The objective of this work was to develop and investigate the 3d-transition metal NiTi shape memory alloy for its transformation temperatures. The alloy was prepared by using chips of metallic Ni and Ti in the vacuum arc melting furnace. Melting was carried out under the protective atmosphere of Argon gas. An ultra-thin sheet (0.3mm) was prepared by cold-rolling the alloy. An intensive cold rolled sheet of NiTi was inspected for structural, microstructure, elemental composition and thermal cyclic behavior using XRD, FE-SEM, EDX and DSC studies respectively. The alloy sheet sample was annealed in the temperature range of (300-900)˚C for 20 minutes. DSC scan was carried out in the temperature range between (200 ̊ C→ -60 ̊ C→ 200 ̊ C for as rolled, annealed and for thermal cycling. In the early stage of annealing, highly diminished martensitic and austenitic peaks in the DSC-thermo gram evidenced that the alloy microstructure structure was under high stress. An optical micrograph revealed the rolled structure of the alloy sheet. DSC examinations further revealed that the cyclic and phase-transformation behaviour of the alloy was significantly influenced by heat treatment. As a result of annealing, the transformation temperatures of austenite and martensite have shifted from 37.922 ̊ C to 61.344 ̊ C and from 53.453 ̊ C to 72.322 ̊ C respectively. The hysteresis between martensite and austenite decreases by 10.978 ̊ C as the annealing temperatures increase. Stable behaviour of transformation temperature is observed after annealing at 650 ̊ C and above. No change in the transformation temperatures was observed during thermal cycling. This study concludes that the variation in the transformation temperatures is the result of stress relief of martensitic plates during annealing treatment. The stable behaviour of transformations temperatures during annealing as well as during thermal cycling is due to dislocation tangling and precipitation. Key Words: Martensitic, hysteresis, ultra-thin sheet, thermal cycling, stress relieving, tangling, cold rolling 1. Introduction Shape Memory Alloys are a subset of blessed materials that have a memory and a highly superelastic character. A MEMORY is something that is rememorized/restored [1- 2]. When a smart material undergoes some deformation and is exposed to a suitable temperature, it magically memorizes its original shape for a prescribed period of time. Whereas super-elasticity is defined as shape recovery after significant deformation upon unloading. Shape memory effects are a common result of shape memory alloys, and as a result of this exceptional effect, shape memory alloys demonstrate a glow to researchers and scientists [4]. These smart alloys have an exclusive characteristic which is responsible for their shape memorization, i.e., a unique phase transformation of their crystallographic structure upon heating and cooling. 3d transition metals, such as the nickel-titanium alloy NiTi, are examples of smart alloys that exhibit shape memory [5]. NiTi-alloys exhibit two-stable phases. The high temperature phase is known as Austenite, and the low temperature phase is known as Martensite. The Base Centered Cubic structure (B2) is the Austenite crystal structure, named after the English physicist, Charles Austen. The crystal structure of martensite is a monoclinic site crystal that has two stable, twinned martensite (B19') and a detwinned martensite (B19), the Martensite phase name subsequent to the German Physicist Adolf Martens'[5-6]. The Martensite crystal structure forms a twinned symmetric structure. Twinning of martensite refers to a structure like a mirror image in which each layer is parted from the other layer through a twinning boundary. The twinned boundaries of a martensite structure have a distinctive ability to undergo some degree of deformation without contravention of atomic [5]. While the Austenite phase is a stronger phase and is not easily deformable, when we apply some mechanical force to the twinned martensite by the application of external mechanical force, the twinned martensite crystal structure switches its orientation to deformed martensite through the movement of the twinned boundaries. The detwinned martensite completely transformed into