Effect of the linear velocity during the melt spinning process on shape memory transformation of Ni-Ti ribbons

2012 ◽  
Vol 1373 ◽  
Author(s):  
E. Nuñez-Mendoza ◽  
E. López Cuellar ◽  
Walman Benicio de Castro ◽  
B. López Walle
Keyword(s):  
Shape Memory Alloys ◽  
Shape Memory ◽  
Melt Spinning ◽  
Solidification Rate ◽  
Linear Velocity ◽  
Vacuum Induction Melting ◽  
Induction Melting ◽  
Scanning Calorimetry ◽  
Spinning Process ◽  
Niti Shape Memory Alloys

AbstractThe usual process to produce NiTi shape memory alloys is vacuum induction melting (VIM). Currently a new alternative process to produce NiTi shape memory alloys by rapid solidification structures called Melt Spinning has been studied. In this work, results of ribbons with a chemical composition Ti-55.2 Ni (wt %) alloy prepared by this method are presented. The ribbons are prepared at two different linear velocities: 30 m/s and 50 m/s. After that, samples are heat treated at 350 °C during 1 hour. The alloys are characterized by Scanning Electron Microscopy (SEM), Differential Scanning Calorimetry (DSC) and X-Ray Diffraction. According to the cycled DSC test, transformation peaks are associated with the B2→R→B19´ transformation during cooling and B19´→R→B2 during heating, showing transformation in multi-peaks. The martensite B19´ start (Ms) is varying from 35 to 39°C and the martensite finish (Mf) from 15 to 21°C, 42-47°C for austenite B2 start (As) and 65-69°C for austenite finish (Af) approximately. All analyzed ribbons show very similar values of transformation hysteresis temperatures at 50% of transformation of around 28°C. In order to change solidification rate, linear velocity is varied during the melt spinning process. Results indicate that linear velocity affects directly the temperature of transformation. When the linear velocity is increasing, crystallographic Ti-rich precipitates are developed, but dendritic growth disappears, changing the microstructure and decreasing these transformation temperatures. Then changes in linear velocity can dramatically affect shape memory properties, and in this case a velocity of 50 m/s produces a more homogenous alloy.

Vacuum induction melting of NiTi shape memory alloys in graphite crucible

2007 ◽  
Vol 465 (1-2) ◽  
pp. 44-48 ◽  
Author(s):  
Niraj Nayan ◽  
Govind ◽  
C.N. Saikrishna ◽  
K. Venkata Ramaiah ◽  
S.K. Bhaumik ◽  
...  
Keyword(s):  
Shape Memory Alloys ◽  
Shape Memory ◽  
Graphite Crucible ◽  
Vacuum Induction Melting ◽  
Induction Melting ◽  
Niti Shape Memory Alloys

Cast NiTi Shape-Memory Alloys

2004 ◽  
Vol 855 ◽  
Author(s):  
Alicia M. Ortega ◽  
Carl P. Frick ◽  
Jeffrey Tyber ◽  
Ken Gall ◽  
Hans J. Maier
Keyword(s):  
Shape Memory Alloys ◽  
Shape Memory ◽  
Grain Orientation ◽  
Mechanical Response ◽  
Complex Geometry ◽  
Low Cost ◽  
Orientation Distribution ◽  
Scanning Calorimetry ◽  
Cast Material ◽  
Niti Shape Memory Alloys

ABSTRACTThe purpose of this study is to investigate the structure and properties of polycrystalline NiTi in its cast form. Although it is commonly stated in the literature that cast NiTi has poor shape-memory behavior, this study demonstrates that with appropriate nano/micro structural design, cast NiTi possesses excellent shape-memory properties. Cast NiTi shape-memory alloys may give rise to a new palette of low-cost, complex-geometry components. Results from two different nominal compositions of cast NiTi are presented: 50.1 at.%Ni and 50.9 at.%Ni. The cast NiTi showed a spatial variance in grain size and a random grain orientation distribution throughout the cast material. However, small variances in the thermo-mechanical response of the cast material resulted. Transformation temperatures were slightly influenced by the radial location from which the material was extracted from the casting, showing a change in Differential Scanning Calorimetry peak diffuseness as well as a change in transformation sequence for the 50.9 at.%Ni material. Mildly aged 50.9 at.%Ni material was capable of full shape-memory strain recovery after being strained to 5% under compression, while the 50.1 at.%Ni demonstrated residual plastic strains of around 1.5%. The isotropic and symmetric response under tensile and compressive loading is a result of the measured random grain orientation distribution. The favorable recovery properties in the cast material are primarily attributed to the presence of nanometer scale precipitates, which inhibit dislocation motion and favor the martensitic transformation.

scholarly journals Effect of Sn Addition on Phase Transformation Behavior of Equiatomic Ni-Ti Shape Memory Alloy

2020 ◽  
Vol 17 (3(Suppl.)) ◽  
pp. 0961
Author(s):  
Ali Abadi Aljubouri ◽  
Safa hasan Mohammed ◽  
Mudhafar ali Mohammed
Keyword(s):  
Phase Transformation ◽  
Shape Memory Alloy ◽  
Shape Memory ◽  
Optical Microscope ◽  
Vacuum Induction Melting ◽  
Induction Melting ◽  
Micro Hardness ◽  
Transformation Behavior ◽  
Scanning Calorimetry ◽  
Phase Transformation Behavior

Sn effect on the phase transformation behavior, microstructure, and micro hardness of equiatomic Ni-Ti shape memory alloy was studied. NiTi and NiTiSn alloys were produced using vacuum induction melting process with alloys composition (50% at. Ni, 50% at.Ti) and (Ni 48% at., Ti 50% at., Sn 2% at.). The characteristics of both alloys were investigated by utilizing Differential Scanning Calorimetry, X- ray Diffraction Analysis, Scanning Electron Microscope, optical microscope and vicker's micro hardness test. The results showed that adding Sn element leads to decrease the phase transformation temperatures evidently. Both alloy samples contain NiTi matrix phase and Ti2Ni secondary phase, but the Ti2Ni phase content decreases with Sn addition and this is one of the reasons that leads to decrease the micro hardness of alloy with adding Sn element in a noticeable manner. The micro hardness decreases from 238.74 for NiTi equiatomic alloy to 202 for NiTiSn alloy after heat treatment.

scholarly journals Vacuum Induction Melting of Ternary NiTiX (X=Cu, Fe, Hf, Zr) Shape Memory Alloys Using Graphite Crucibles

2006 ◽  
Vol 47 (3) ◽  
pp. 661-669 ◽  
Author(s):  
Zhonghua Zhang ◽  
Jan Frenzel ◽  
Klaus Neuking ◽  
Gunther Eggeler
Keyword(s):  
Shape Memory Alloys ◽  
Shape Memory ◽  
Vacuum Induction Melting ◽  
Induction Melting

Influence of Heat Treatments on a NiTi Shape Memory Alloy Obtained Using Vacuum Induction Melting and Reprocessed by Plasma Skull Push-Pull

2015 ◽  
Vol 1765 ◽  
pp. 121-126 ◽  
Author(s):  
Jackson de Brito Simões ◽  
Francisco Fernando Roberto Pereira ◽  
Jorge Otubo ◽  
Carlos José de Araújo
Keyword(s):  
Shape Memory Alloy ◽  
Shape Memory ◽  
Electrical Resistance ◽  
Heat Treatments ◽  
Vacuum Induction Melting ◽  
Niti Shape Memory Alloy ◽  
Induction Melting ◽  
Thermal Treatments ◽  
Scanning Calorimetry ◽  
Thermally Induced

ABSTRACTShape memory alloys (SMA) are metallic attractive engineering materials due to their capacity to store pre-defined shapes through a thermally induced phase transition from a solid state. This paper aims to evaluate the influence of solubilization thermal treatments on a NiTi shape memory alloy originally fabricated by vacuum induction melting and then reprocessed by plasma melting followed by injection molding (Plasma Skull Push Pull process) into different metal molds (steel, aluminum, brass and copper) in order to compare the thermal properties regarding to its raw state. The thermal treatments of solubilization were carried out at 850°C in different times (2n function, n = 0, 1, 2 and 3, in hours). The influence of solubilizing treatments in the NiTi shape memory alloy was analyzed using the following characterization techniques: Differential Scanning Calorimetry (DSC) and Electrical Resistance as a function of Temperature (ERT). The results demonstrate that the solubilization heat treatments applied on the reprocessed NiTi shape memory alloy through the plasma skull push pull process, provides important changes in the phase transformation of the material. Therefore, it was demonstrated that it is necessary to solubilize the material after melting or remelting the NiTi shape memory alloy via this process to obtain mini-actuators products with homogeneous properties.

Synthesis and Characterization of Cu-Al-Be-Mn Quaternary Shape Memory Alloys Prepared by Induction Melting Technique

2015 ◽  
Vol 813-814 ◽  
pp. 240-245 ◽  
Author(s):  
A.G. Shivasiddaramaiah ◽  
U.S. Mallikarjun ◽  
S. Prashantha
Keyword(s):  
Shape Memory Alloys ◽  
Shape Memory ◽  
Low Cost ◽  
Optical Microscope ◽  
Synthesis And Characterization ◽  
Induction Melting ◽  
Ingot Metallurgy ◽  
Scanning Calorimetry ◽  
Β Phase

Shape memory materials are stimuli-responsive materials. They are widely used in military, medical, safety, and robotics applications. Until recently, only Ni-Ti based SMA’s are commercially used due to its relatively ease of manufacturing. However, the exorbitantly high cost of Ni-Ti based SMA limits its application to niche markets such as medical stents, aerospace and defence. Recently, it is found that Cu based alloys exhibit shape memory behavior. Out of which, Cu-Al-Be-Mn is most interesting SMA in terms of less process complexity and low cost. Cu–Al–Be-Mn shape memory alloys in the range of 09–15 wt.% of aluminium and 0.1-0.4 wt.% of Beryllium and 0.1 to 0.3 wt.% of Manganese, exhibiting β-phase at high temperatures and manifesting shape memory effect upon quenching to lower temperatures, were prepared through ingot metallurgy. The alloy ingots were homogenized followed by step quenching so as to obtain a structure that is completely martensitic. They were subsequently characterized by X-ray diffractogram (XRD), Differential Scanning Calorimetry (DSC) and Optical Microscope (OM). The shape memory properties of the alloys were studied by bend test. This paper emphasizes the synthesis and characterization of the Cu-Al-Be shape memory alloys.

Influence of Thermomechanical Treatment on Transformation Temperatures of Cu-Al-Ni Shape Memory Alloys

2008 ◽  
Vol 59 ◽  
pp. 92-100
Author(s):  
Ana Cris R. Veloso ◽  
Rodinei Medeiros Gomes ◽  
Dagoberto Brandao Santos ◽  
I.C.E.G. Lima ◽  
Severino Jackson Guedes de Lima ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Differential Scanning Calorimetry ◽  
Shape Memory Alloys ◽  
Shape Memory ◽  
Thermomechanical Treatment ◽  
Hot Rolling ◽  
Rolling Process ◽  
Induction Melting ◽  
Scanning Calorimetry ◽  
Transformation Temperatures

In this study Cu-13.8Al alloys with 3.0% and 4.0% (wt%) of nickel were obtained by induction melting. The effect of homogenization heat treatment and hot rolling on the transformation temperatures of these alloys was investigated by differential scanning calorimetry. It was observed that the transformation temperatures increase with long homogenization times, and also by hot rolling, and this displacement is smaller for alloys with 4.0% of nickel. In both alloys in the quenched state, the reversion reaction is characterized by the appearance of multiple peaks attributed to the presence of martensites 2H and 18R. The influence of the rolling process must be associated with the loss of Ni and Al during the process.

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