Faculty Publications
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Item Influence of Gd on the microstructure, mechanical and shape memory properties of Cu-Al-Be polycrystalline shape memory alloy(Elsevier Ltd, 2018) Bala Narasimha, B.N.; Murigendrappa, S.M.In the present study, the influence of rare earth element gadolinium (Gd) on Cu-Al-Be polycrystalline shape memory alloy has been investigated. Cu 88.13 Al 11.42 Be 0.45 ternary alloy with addition of Gd from 0.05 to 0.15 wt% has been used for investigation. The tests have been carried out for microstructure, morphology, ductility, phases, crystal structure, phase transformation temperatures and shape recovery ratio. Refinement of the grain size resulted as gadolinium increased from 0 to 0.08 wt%, the grain size decreases from 463.45 to 81.80 µm with reduction of 82.34%. The tensile strength has increased from 398.93 to 581.42 MPa with improvement in the ductility from 10.05% to 23.72% at 0.08 wt% gadolinium. The phase transformation temperatures increases as gadolinium increases and reduction in shape recovery ratio from 97% to 65%. © 2018 Elsevier B.V.Item An investigation on the properties of boron modified Cu–Al–Be polycrystalline shape memory alloys(Elsevier Ltd, 2020) Bala Narasimha, G.; Murigendrappa, S.M.Effect of microalloying of boron (B) i.e., 0.02–0.15 wt% and the variation of composition of Al and Be from 11.3 to 11.9 wt% and 0.41–0.44 wt% respectively, has been investigated on the grain refinement and shape memory properties of polycrystalline Cu–Al–Be shape memory alloy. The tests have been carried out for microstructure, morphology, phases, crystal structure, phase transformation temperatures and shape recovery ratio. The investigation results in boron has strong impact on grain refinement with minimal addition, followed by Al and Be. AlB2 acts as heterogeneous nucleation site in grain refinement and it increases with increase in B and Al. Transformation temperatures increases with boron up to 0.08 wt% and then decreases, whereas increase in Al and Be decreases the temperatures. Doping and increasing of boron up to 0.15 wt% exhibits complete shape recovery, whereas Be < 0.42 wt% and Al < 11.8 wt% exhibits poor recovery ratio. © 2020 Elsevier B.V.Item Investigation on Properties of Shape Memory Alloy Wire of Cu-Al-Be Doped with Zirconium(Springer, 2020) Singh, R.K.; Murigendrappa, S.M.; Kattimani, S.Abstract: In this paper, the effect of wire drawing on the microstructures, mechanical properties, and shape memory effect of compositions Cu87.85-Al11.70-Be0.45 (CAB) and Cu87.73-Al11.70-Be0.45-Zr0.12 (CABZ) has been experimentally investigated. The wires with a diameter of 1.33 mm are manufactured from the casted round bars through the rolling and drawing (secondary) process. Investigations are performed on microstructure and phase for both as-cast and wire-drawn SMAs. Further, wire-drawn SMAs are investigated for phase transformation temperatures, hardness, ductility, and shape memory effect. The results show that the average grain size decreased with 73.06% by adding Zr to the CAB alloy. Further, the grain size of CABZ alloy wire decreased with 67.38% in the longitudinal direction and 67.07% in the transverse direction as compared to CAB alloy wire after the secondary process. Improvement of the grain structure in CABZ alloy wire resulted in an enhancement in the hardness of 13.86% in longitudinal and 12.43% in the transverse direction, and tensile strength of 134.58% and ductility of 177.06%. The phase transformation temperatures reduced by the addition of Zr, and better shape recovery is observed in CABZ alloy wire. Graphic Abstract: [Figure not available: see fulltext.] © 2020, ASM International.Item Effect of manganese and homogenization on the phase stability and properties of Cu–Al–Be shape memory alloys(Elsevier Editora Ltda, 2021) Bala Narasimha, G.; Murigendrappa, S.M.In this study, the effect of addition of manganese to the ternary Cu–Al–Be shape memory alloys on phase stability, phase transformation temperatures, microstructure, morphology and grain size has been investigated. Secondly, the effect of betatization temperatures and time period has been investigated on the phases and properties of Cu–Al–Be–Mn SMAs. Results reveal that the addition of manganese in the alloys with Al ? 11.8 wt.% forms coexistence of ?1? and ?1? martensites, and manganese ?1 wt.% forms austenite ?1 (DO3). DSC studies exhibit two stage reverse transformation attributes to coexistence of martensites. Increase in manganese decreases the transformation temperatures and increase in betatization temperature and time increases transformation temperatures. Alloying manganese didn't exhibit significant grain refinement and results reduced shape recovery due to the coexistence of martensites. © 2021 The Author(s)Item An experimental evaluation of the microstructure, mechanical and functional fatigue properties of the boron-doped Cu-Al-Be SMA wires(Elsevier Ltd, 2021) Singh, R.K.; Biswas, P.; Murigendrappa, S.M.; Kattimani, S.An experimental evaluation of the microstructure, mechanical and functional fatigue properties of the Cu-11.70Al-0.45Be doped with Bx (x = 0.05, 0.10, 0.12, and 0.14 wt%) SMA wires has been carried out. The experiments were performed to investigate microstructure, phase/precipitates, and transformation temperatures for both as-cast and wire samples. Furthermore, tensile properties, shape recovery ratio, and functional fatigue evaluation have also been carried out for the wire samples. The investigation shows that the addition of the minor amount of boron and secondary processes involved during the specimen preparation induced excellent grain refinement. The addition of boron decreased transformation temperatures; however, there was not a considerable change observed due to the secondary process. It was observed that tensile properties increases with the boron addition, and complete shape recovery was observed for all the selected alloys. Finally, functional fatigue tests were conducted under constant stress condition and observed that the number of cycles until the failure has increased and more distance recovery was achieved with an increase in boron doping. © 2021Item Effect of Cerium and Aluminium on the phase stability and properties of polycrystalline Cu-Al-Be shape memory alloys(Elsevier Inc., 2022) Bala Narasimha, G.; Murigendrappa, S.M.This study presents the outcomes of an investigation of the effect of wt% of cerium and Aluminium on the phases, crystal structure, microstructure, morphology, phase transformation temperatures, shape recovery ratio and mechanical properties of the polycrystalline Cu-Al-Be shape memory alloys (SMAs). SMAs exhibit martensite phase at room temperature up to 0.49 wt% of Be and ≥ 0.52 wt% of Be transforms to austenite phase. An increase in cerium by 0, 0.05, 0.1, 0.15 and 0.2 wt% decreases the grain size by 0, 70.87%, 82.73%, 83.8% and 94.6%, respectively. An increase in cerium increases the transformation temperatures owing to the Al-rich secondary precipitates, and the shape recovery ratio reduces. Alloying cerium of 0.1 wt% exhibits a maximum tensile strength of 474 ± 23 MPa with the ductility of 24.11 ± 1.42%. © 2021 Elsevier Inc.