Novel Functional Behaviors: Beyond Shape Memory Effect & Superelasticity: Poster Session
Program Organizers: Ibrahim Karaman, Texas A&M University

Monday 5:30 PM
July 10, 2017
Room: Crystal Ballroom A
Location: Hyatt Regency Chicago

P1-32: Application of Taguchi Method for Optimizing Wear Behaviour of a Cu-15.5wt.%Al-5wt.% Ni Shape Memory Alloy : Sampath Vedamanickan1; Adarsh S.H.1; 1Indian Institute of Technology Madras
    Shape memory alloys show good wear resistance apart from exhibiting functional properties: shape memory effect and superelastic effect. But the wear behaviour of Cu-based SMAs has not been explored hitherto. A study on wear of SMAs will be useful for many applications. This paper therefore reports on optimization of the wear behaviour of a Cu-based SMA by varying speed, sliding distance and load using Taguchi method. A Taguchi orthogonal array was designed with three levels of parameters using software Minitab 15. Analysis Of Variance was carried out to identify the critical factors from among speed, sliding distance and load that affect wear behaviour. Finally, a regression model for wear rate was developed as a function of these parameters. It was found that the wear rate was more dependent on load and speed than on sliding distance for the alloy. Keywords: Taguchi method, shape memory alloy, wear rate, software Minitab 15.

P1-34: On the Precipitation Kinetics of a Near Equiatomic NiTi Alloy during Different Heat Treatments: Guilherme Pandolfi1; Suzanny Martins1; Leandro Santos1; Vicente Buono1; 1UFMG
    Aging treatments of near equiatomic NiTi alloys lead to formation of metastable precipitates as Ti3Ni4 and Ti2Ni3. Since the Ti3Ni4 is a coherent precipitate and the Ti2Ni3 an incoherent precipitate the mechanical properties of an aged NiTi alloy depend on which precipitate is formed. Furthermore, the precipitation process decreases the Ni content of the matrix, which may result in stabilization of martensite at room temperature, that is, a NiTi alloy initially superelastic can present after aging shape memory effect. NiTi wires were aged for 1 hour at temperatures among 300°C and 600°C. The martensitic transformation temperatures and stable phases at room temperature were studied by using DSC and XRD, respectively. The mechanical properties were evaluated by means of uniaxial tensile tests, while the microstructure was analyzed by TEM. The results showed that aging at intermediate temperatures were responsible for the best shape memory effect.

P1-35: Phenomenological Models for Predicting δ-phase Region in Fe-Mn-Si-Cr-Ni Shape Memory Alloys: Gaixia Wang1; Huabei Peng2; Shanling Wang1; Yuhua Wen1; 1Sichuan University; 2Sichuan University / University of Glasgow
    Fe-Mn-Si-based shape memory alloys (SMAs) exhibit lower cost, better workability, and better weldability as compared with Ni-Ti-based and Cu-based SMAs. However, processed Fe-Mn-Si-based SMAs suffer from a poor shape memory effect. Special treatments, i.e. training, thermo-mechanical treatment and aus-forming, have to be performed to improve their shape memory effect. Recently, a novel training-free processed Fe-Mn-Si-Cr-Ni SMAs was developed utilizing δ → γ phase transformation. Nevertheless, phase diagram of Fe-Mn-Si-Cr-Ni SMAs has not been established so far. In the present paper, effect of alloying elements on staring temperature (δs) and finish temperature (δf) of γ-phase to δ-phase transformation was investigated. According to the above results, phenomenological models were developed for predicting δ-phase region in Fe-(13-25)Mn-(4.5-6.5)Si-(7-12)Cr-(2-8)Ni-(0.006-0.140)C SMAs. These models will lay the foundation for fabricating training-free processed Fe-Mn-Si-Cr-Ni SMAs using δ → γ phase transformation. In addition, they can be used to design heat treatment process for high-Mn austenitic stainless steels.

P1-36: The Stress Induced Martensitic Transformation Behavior of TiNi/TiNiNbFe SMAs Laminated Composite: Xiaowei Hu1; Daqiang Jiang1; Fangmin Guo1; Yang Ren2; Lishan Cui1; 1China University of Petroleum-Beijing; 2Argonne National Laboratory
    Two kinds of shape memory alloys TiNi and TiNiNbFe with different martensitic transformation temperatures were laminated by hot pressing, forging, rolling and drawing. The microstructure, transformation behaviors and mechanical properties of the material were studied by SEM, DSC, tensile test and in-situ high-energy X-ray diffraction technique. The results indicated that the thickness of the TiNi and TiNiNbFe laminates are 8µm and 4µm respectively. After annealing of the cold-drawn wire, the TiNi laminate could show B2→R and R→B2 transformation upon cooling and heating, while the TiNiNbFe laminate does not show any transformation even cooling to liquid nitrogen temperature. The composite exhibits a phase transformation critical stress of 1 GPa and a plasticity of 16%.The in-situ high energy XRD results show that the stress-induced martensitic transformation of TiNiNbFe was synchronized with that of TiNi, though the former has much lower martensitic transformation temperature.

P1-37: Transmission Evaluation of Tensions through NiTi Abutments to the Dental Implant and Cortical Bone by the Finite Element Method: fernanda gonçalves1; osmar santos1; luiz fernando goncalves1; tarcisio jose paes junior2; Alexandre borges2; jorge otubo1; 1Instituto Tecnologico de Aeronautica; 2UNESP- INSTITUTO DE CIENCIA E TECNOLOGIA
    Excessive loads on dental implants may lead to decreased crest Bone resorption or fracture components system. The reduction in transmission of masticatory impacts to the adjacent bone implant is a challenge for the development of new materials for this application. Finite element method simulations can study the tensions produced by the loads in the alveolar bone. This work aimed to make a nonlinear analysis of an abutment model made of superelastic NiTi alloy, using the ANSYS software, and to simulate the effect of masticatory loads. In particular, the transmission of forces to implant and consequently adjacent bone is evaluated, in order to quantify the energy absorption by the material. The energy dissipation in the implant can function as safety system of the implant, preventing the breaking of components and decreasing the loss of marginal bone crest. Dynamic studies should be performed to analyze the behavior of NiTi against masticatory impacts

P1-38: Ultrahigh Damping Capacity Associated with Complex Microstructure of Ni-Ti Shape Memory Alloy Wires: Jin Mingjiang1; 1Shanghai Jiao Tong University
    The Ni-Ti alloys are known as the most developed shape memory alloys due to their many practical applications on the shape memory effect, pseudo-elasticity and high mechanical damping capacity. In this manuscript, the microstructure of the Ni-rich Ni-Ti cold-drawing wires was regulated by various annealing and aging treatments and the corresponding mechanical spectra were characterized. Results showed that an ultrahigh damping capacity of about Q−1=0.38 was observed existing over a temperature range of about 80K around room temperature as the Ni-Ti wires were annealed at 973K for 4.5h followed by aging at 523K for 24h. The corresponding microstructure of the aged Ni-Ti wires are investigated by in-situ XRD and TEM. The huge damping capacity is believed associated with the existence of intermediate rhombohedral R phase, in which no Ni4Ti3 precipitates were observed.

P1-39: Study on the Influence of Thermal Cycle on the Internal Friction Properties of the Mn82.2Cu15.8Al2 Alloy: Wenyi Peng1; Cuizhen Deng1; Yulong Sun1; Lin Chen1; Rui1; Yan Gong1; 1School of Materials Science and Engineering, Nanchang University
    The internal friction of 82.2Mn-15.8Cu-2Al(wt%) alloy after the thermal cycle(Room temperature -743K))of different times was investigated. The internal friction was measured using multifunctional internal friction equipment. The microstructure was observed by scanning electron microscopy. The phase structure was determined by X-ray diffraction profile. The thermal behavior was determined by differential scanning calorimetry. The results indicate that with the increase of thermal cycles,the Spinodal decomposition will occurs with rich Mn and Cu phase and -Mn phase. We calculated the activation energy and the relaxation factor of the low temperature side internal friction peak. Using the peak separation method to isolate the internal friction peak, which is caused by mutual coupling of martensitic transformation and antiferromagnetic transition.