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Effect of Te Addition on Transformation Temperature and Thermal Properties of Cu-14%Al-4.5%Ni Shape Memory Alloy
Available online at www.sciencedirect.com
ScienceDirect Materials Today: Proceedings 18 (2019) 2242–2249
www.materialstoday.com/proceedings
ICMPC-2019
Effect of Te Addition on Transformation Temperature and Thermal Properties of Cu-14%Al-4.5%Ni Shape Memory Alloy Raad Suhail Ahmed Adnana * a
Univeristy of Technology –Iraq ,Department of Materials Engineering, 10066 ,Baghdad,Iraq
Abstract This study to investigate the effect of adding 0.3% ,1% and 3% Te to Cu-14%Al-4.5%Ni shape memory alloy in three deferent percentages (0.3,1,3)% and to analyze the effect of addition on transformation temperature and thermal properties , the alloys were fabricated by casting the homogenized and machined by EDM , also Chemical Analysis ,SEM-EDS , XRD and DSC were performed to the alloys Then Enthalpy was calculated by means of area under the curve form the DSC charts also specific heat and Grain Size by Debye---Scherer equations then the calculations of activation energy both by Ozawa and Kissinger equations Results showed an increase in the transformation temperature and in enthalpy and a decrease in the activation energy calculated using Ozawa and Kissinger equations © 2019 Elsevier Ltd. All rights reserved. Selection and peer-review under responsibility of the 9th International Conference of Materials Processing and Characterization, ICMPC-2019 Keywords: Shape Memory Alloys;Shape Memory effect , Transformtion Temperature , Thermal Properties , Activation Energy
1. Introduction In the last decade, the Shape Memory Alloys SMAs have been in considerable focus because of their potential innovative applications. The Cu-ternary SMAs have attracted particular attention since they are a decent substitute for Ni-Ti SMAs particularly in non-medicinal applications, e.g., the field of coupling and latches [1],Designing the SMA applications is progressively throughout the years the SMA Actuators are 25 a greater number of times than electrical actuators in work thickness [2] . The Cu-put together SMA are more with respect to request especially in non-medicinal application for monetary reasons in view of the low change temperatures (- 100 to 100 °C) and high delivering expense of NiTi Alloy render their utilization for some applications, particularly high-temperature
* Corresponding author. Tel.: +96407901329466 E-mail address: [email protected] 2214-7853 © 2019 Elsevier Ltd. All rights reserved. Selection and peer-review under responsibility of the 9th International Conference of Materials Processing and Characterization, ICMPC-2019
R.S.A. Adnan / Materials Today: Proceedings 18 (2019) 2242–2249
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Nomenclature As Af Ms Mf T° Ap Mp D Cp Ea Eb ΔH ΔS ΔG
Austenite start temperature °C Austenite finish temperature °C Martensite start temperature °C Martensite finish temperature °C Equilibrium temperature °C Austenite peak temperature °C Martensite peak temperature °C Grain size (μm) Specific heat Activation energy Ozawa equation (J) Activation energy Kissinger equation (J) enthalpy J·g-1 entropy J·g-1·C-1 Free energy J
applications, unfeasible. Hence, Cu–Al–Ni SMAs are the most popular effective alternatives to NiTi because of their high Transformation temperatures (-200 to 300 °C), low cost, and high transformation temperature However, the brittleness [3], low quality, substantial versatile anisotropy, and extensive grain measure thwart their practical applications. ,in spite of the fact that the fragility can hold an issue in machining yet that can be settled in EDM or wire cutting .the quadric and fifth component added to the composite is in charge of the adjustment in the combination and properties[4],so including components can improve mechanical properties or for a fine grain estimate or the shape memory properties and impact or erosion opposition . Either by framing new stages or precipitation of the component in which can broaden as far as possible or the hysterics circle by framing the β – stage and making it progressively stable, the high temperature shape memory compounds (HTSMA) as a rule between 200-300 °C are not many so the goal is having the composite to achieve this point of confinement and past the space .most works, for example, Sari [5] contcetrated either on including components, for example, Mn and Ti (above 1% ) and their impact on mechanical properties. Saud et al. [6-7] considered the impact of small amounts of alloying components such Co and Fe (below 1%) on the structure and properties of Cu-based SMA composites.
2.Experimental Work 2.1.Materials and procedures Pure Cu (99.99% purity) wires, Al (99.99% purity) foils, and Ni (99.99% purity) powder were melted in a vacuum induction furnace under an argon atmosphere at 1200 °C, and then, the melt was poured into a cylindrical alloy steel die (1.4 cm in diameter). Then, it was re-melted and 0.3%, 1.0%, 3.0% Sn was added and stirred at 1100°C. Homogenization was carried out at 900 ° C for 30 min and then the samples were quenched in an iced brine(90%H2O-10%NaCl) solution. Then, they were wire cut into specimens with 0.5 cm height for SEM, DSC, and XRD measurements. The chemical compositions of the as-cast and homogenized specimens are listed in Table 1. Table 1 Chemical Composition of SMA
Alloy
Te%
Al%
Ni%
Base SMA
---
14
4.5
Cu% Rem
T1 T2 T3
0.3 1 3
14 14 14
4.5 4.5 4.5
Rem Rem Rem
.
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R.S.A. Adnan / Materials Today: Proceedings 18 (2019) 2242–2249
2.2 XRD and SEM –Optical Microscope
XRD was performed by using Shimadzu 3000 XRD EDX Instrument Cu Target Cu(α) λ=1.45 A°,Then, the grain size was calculated using the Debye---Scherrer equation [4]. 0.9λ (1) D= B / Cos Θ where λ is the wavelength of the X-ray (Cu Kα radiation), B is the peak full width at half maximum, and θ is the Bragg angle. For the microstructure examination, the specimens were ground and polished and etched in a solution that consists of FeCl3·6H2O + HCl + methanol, and then, examination was performed using for 4 min and then microstructure by Kruss optical microscopy & Tescan easy probe SEM –with attached Oxford EDS 2.3 DSC Test DSC was preformed using SATRAN Lab-SYS 300 with a range of 25—250 °C) in both directions exothermic and endothermic result were exported to Microsoft EXCEL to calculate the equilibrium temperature using equation (1) [1]. °=
(
+
)
(2)
Results were imported into Microsoft EXCEL to calculate the enthalpy (ΔH) as the area under the curve. Then, a mathematical model was prepared to calculate the entropy (ΔS) as the free energy (ΔG), as shown in equation (4) [5] ∆ ∆ = (3) (4) ∆ =∆ − ∆ After the measurements, the specific heat capacity values were calculated using the SATRAN LabSYS 300 Device Data by applying; (dQ/dt) is the heat flux given by the DSC curve, m is the mass of sample, (dT/dt) is the heating rate of the sample, T is the temperature, and t is the time. Then, the activation energy was calculated using the model proposed by Ozawa [4]: (log ∅) − (5) = 1/ where b is a constant (0.4567) and R is the universal gas constant. In addition, the model proposed by Kissinger [5] is as follows: -
=
.
(
/ /
)
(6)
where .. is the heating rate and Tm is the maximum temperature of the DSC peak [5]. 3.Results and Discussions The XRD results shown in Figures (1), (2), (3), and (4) indicate the main AlCu3 phase and Al7Cu23Ni. There is a shift in the chart with the increase in the Te content. The formation of an intermetallic compound, the stabilization of the β` and γ` phase, and the increase in the intensity from 4000 to 8000 CPS indicate that the shifting is due to the addition of Te[8]
R.S.A. Adnan / Materials Today: Proceedings 18 (2019) 2242–2249
Fig 1 XRD results for base SMA
Fig .3 XRD results for T2 SMA
2245
Fig .2 XRD results for T1 SMA
Fig .4 XRD results for T3
3.2 SEM and Optical Microscopy SEM images showed both stacked piles in pairs or Four piles martensite (γ`) and the needle-like martensite (β`). The Te particles were non-homogenously distributed in the matrix. With the increase in the Te content, the β Phase is restrained be the distribution of the Sn grains, in particular the smaller size martensite in manner similar to Saud et.al[9] concluded in the use of B particles also it also restrained the martensite phases. EDS results shown in Figure (5) (6) confirmed the chemical composition of the alloys. Figure (7) (8) and Figure (9) shows the Debye-Scherrer equation results: a slight increase in the grain size with increasing Te content during homogenization because of the limited function of Homogenization Treatment .
Fig 5 SEM and optical microscopy image of base SMA
Fig 6 Optical microscopy image of T1 Alloy
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R.S.A. Adnan / Materials Today: Proceedings 18 (2019) 2242–2249
Fig 7 SEM and optical microscopy image of T2 SMA
Fig 8 SEM and optical microscopy image of T3 Alloy
Fig. 9 EDS results for T3 alloy
Fig. 10 Debye–Scherrer equation results
R.S.A. Adnan / Materials Today: Proceedings 18 (2019) 2242–2249
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3.3 DSC Results Table (2) shows the shape memory properties; it shows an increase in the transformation temperature in figures (10,11,12, and 13 ) shows DSC curves of base and Te added SMAs the domain is in range and also the peak level is less as similar behavior as Ti in small amounts[9], the case of T1 above the domain (100-170) °C Due to the effect of Te addition while in T2 Alloy there is a limited shifting in the case of the end transformation temperature Mf and Af Due to the Te effect was halted by the γ ` phase is more dominating than β ` phase,with an increase in the equilibrium temperature as shown in figures(10),(11),(12) and (13) ,(14) respectively[8]. Also, the peak temperature increased in the endothermic direction, while it decreased in the exothermic direction, which were in agreement with the results of Adnan et al. [7]. Table (2) Shape memory effect results Alloy\Temperature
As°C
Af°C
Ms°C
Mf°C
T°
Ap°C
Mp°C
SMA
129
165
133
100
149
144
110
T1
215
242
109
92
176
230
109
T2 T3
181 150
199 186
129 165
76 127
165 176
190 170
100 150
Fig (11) Thermogram of base SMA
Fig (13) Thermogram of T2 SMA
Fig(12) Thermogram of T1 SMA
Fig(14) Thermogram of T3 SMA
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R.S.A. Adnan / Materials Today: Proceedings 18 (2019) 2242–2249
The results were exported into Microsoft EXCEL. Equations 1–6 were applied to calculate the enthalpy (ΔH), entropy (ΔS), and free energy (ΔG) for the base alloys with the addition of Te after calculating (ΔH) by means of area under the curve and substituting equation 3 into equation 6 to calculate the entropy and activation energy. Results are shown in Tables 3 and 4. The results show an increase in the enthalpy and decrease in the entropy in the exothermic direction with an increase in the Sn content, and a decrease in the Enthalpy and Entropy in the endothermic direction this is a result to the addition of Te .As for the case of the results of the activation Te Addition showed a decrease in activation energy that the thermo-mechanical transformation is less required while with the increase of maximum temperature and equilibrium temperature , Te is a High melting point element so with this characterization the energy is lowered more with Te Increase of percentage.in both equations The transformation of the SMAs is related to the energy which the materials retain in their structure. Therefore, this energy consists of the chemical energy and reversible mechanical energy and T is the temperature at which the chemical energies of austenite and martensite phases are equal [7] Table .3 Results of mathematical modelling for thermal properties of SMA Alloy
ΔH M-A /J·g-1
ΔH A-M /J·g-1
ΔSM-A /J·g-1 C°-1
ΔSA-M /J·g-1 C°-1
SMA
1.9
-2.54
0.12
-0.17
T1
3.375
-2.9
0.022
-0.019
T2
8.025
-6
0.045
-0.036
T3
32.5
-15
0.184
-0.085
The activation energies were calculated for the reverse transformation according to Kissinger and Ozawa methods and are given in Table 4. The activation energy decreased with increased Te content; these results agree with the results reported by Ahmed Adnan et al. [7]. Table. 4 Activation energy for the base and SMA alloys with Te Alloy
T°C
Ea(j)
Eb(j)
Base
149
-22.5661
-21.1182
T1
176
-25.81623
-24.8113
T2
165
-23.68461
-22.0784
T2
176
-35.52692
-29.4834
R.S.A. Adnan / Materials Today: Proceedings 18 (2019) 2242–2249
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The specific heat readings obtained from the DSC device showed a decrease in the exothermic direction with a decrease in both direction exothermic and endothermic with an slight increase in the Specific heat at 0.3% Te it’s unexplainable as show in below fig 15.
Fig .15 Relationship between specific heat and Te content
4. Conclusions 1. With Te addition, the transformation temperature shifted for the base alloy and the equilibrium temperature increased. 2. Te particles were non-homogenously distributed in the matrix. This restricted martensite growth in the matrix. 3. The addition of Te increased the enthalpy of the shape memory alloys and decreased the entropy in the exothermic direction and vice versa. 4. Te Addition lowered the activation energy as per both Ozawa and Kissinger equations in the exothermic direction. 5. Te addition lowered the specific heat (Cp) of the SMA in most cases. 6. Te Addition with homogenization increased the grain size. Acknowledgements The author would like to thank the staff of the XRD Laboratory in the Nano Technology Center, the DSC Laboratory in the Department of Materials Engineering, SEM-ESD Laboratory in the Department of Production Engineering and Metallurgy at The University of Technology-Iraq. References [1] L’excellent Christian 2007 Shape Memory Alloy Handbook (New York: John Wiley and Son), P. 2 [2] J.J. Mohd, M. Leary, and A. Sibic, Materials and Design, 56, 6, 2014 [3] A. Agrawal and R.K. Dube, Journal of Alloys and Compounds, 750, 235-247, 2018 [4] Z. Karagoz and C. Aksu Canbay, Thermal Analysis Calorimetry, 114, 1069-1074, 2013 [5] C. Aksu Canbay and C,Z. Karagoz, International Journal Thermophysics, 34, 1325-1335, 2013 [6] I.N. Qader, M. Kok, and F. Dağdelen, Physica B: Physics of Condensed Matter, 2018 [7] R.S.Ahmed Adnan and M.M. Abudlbakki “The effect of Sn addition on Transformation Temperature and Thermal Properties of Cu-Al-Ni Shape m emory alloy”,IOP Conference Series: Materials Science and Engineering, 454 ,1, 12050,2018) [8] M.K. Abbass, M.M. Radhy, R.S.A. Adnan, International Journal of Advances in Science, Engineering and Technology(IJASEAT), 4,2, 161164, 2016 [9] S. Saud. ,E. Hamza T. Abubakar T, M.K.Ibrahim.,A. Bahador, Metallurgical and Materials Transactions A , 47A, 8 2016 s. Research , 30,14,2015
ScienceDirect Materials Today: Proceedings 18 (2019) 2242–2249
www.materialstoday.com/proceedings
ICMPC-2019
Effect of Te Addition on Transformation Temperature and Thermal Properties of Cu-14%Al-4.5%Ni Shape Memory Alloy Raad Suhail Ahmed Adnana * a
Univeristy of Technology –Iraq ,Department of Materials Engineering, 10066 ,Baghdad,Iraq
Abstract This study to investigate the effect of adding 0.3% ,1% and 3% Te to Cu-14%Al-4.5%Ni shape memory alloy in three deferent percentages (0.3,1,3)% and to analyze the effect of addition on transformation temperature and thermal properties , the alloys were fabricated by casting the homogenized and machined by EDM , also Chemical Analysis ,SEM-EDS , XRD and DSC were performed to the alloys Then Enthalpy was calculated by means of area under the curve form the DSC charts also specific heat and Grain Size by Debye---Scherer equations then the calculations of activation energy both by Ozawa and Kissinger equations Results showed an increase in the transformation temperature and in enthalpy and a decrease in the activation energy calculated using Ozawa and Kissinger equations © 2019 Elsevier Ltd. All rights reserved. Selection and peer-review under responsibility of the 9th International Conference of Materials Processing and Characterization, ICMPC-2019 Keywords: Shape Memory Alloys;Shape Memory effect , Transformtion Temperature , Thermal Properties , Activation Energy
1. Introduction In the last decade, the Shape Memory Alloys SMAs have been in considerable focus because of their potential innovative applications. The Cu-ternary SMAs have attracted particular attention since they are a decent substitute for Ni-Ti SMAs particularly in non-medicinal applications, e.g., the field of coupling and latches [1],Designing the SMA applications is progressively throughout the years the SMA Actuators are 25 a greater number of times than electrical actuators in work thickness [2] . The Cu-put together SMA are more with respect to request especially in non-medicinal application for monetary reasons in view of the low change temperatures (- 100 to 100 °C) and high delivering expense of NiTi Alloy render their utilization for some applications, particularly high-temperature
* Corresponding author. Tel.: +96407901329466 E-mail address: [email protected] 2214-7853 © 2019 Elsevier Ltd. All rights reserved. Selection and peer-review under responsibility of the 9th International Conference of Materials Processing and Characterization, ICMPC-2019
R.S.A. Adnan / Materials Today: Proceedings 18 (2019) 2242–2249
2243
Nomenclature As Af Ms Mf T° Ap Mp D Cp Ea Eb ΔH ΔS ΔG
Austenite start temperature °C Austenite finish temperature °C Martensite start temperature °C Martensite finish temperature °C Equilibrium temperature °C Austenite peak temperature °C Martensite peak temperature °C Grain size (μm) Specific heat Activation energy Ozawa equation (J) Activation energy Kissinger equation (J) enthalpy J·g-1 entropy J·g-1·C-1 Free energy J
applications, unfeasible. Hence, Cu–Al–Ni SMAs are the most popular effective alternatives to NiTi because of their high Transformation temperatures (-200 to 300 °C), low cost, and high transformation temperature However, the brittleness [3], low quality, substantial versatile anisotropy, and extensive grain measure thwart their practical applications. ,in spite of the fact that the fragility can hold an issue in machining yet that can be settled in EDM or wire cutting .the quadric and fifth component added to the composite is in charge of the adjustment in the combination and properties[4],so including components can improve mechanical properties or for a fine grain estimate or the shape memory properties and impact or erosion opposition . Either by framing new stages or precipitation of the component in which can broaden as far as possible or the hysterics circle by framing the β – stage and making it progressively stable, the high temperature shape memory compounds (HTSMA) as a rule between 200-300 °C are not many so the goal is having the composite to achieve this point of confinement and past the space .most works, for example, Sari [5] contcetrated either on including components, for example, Mn and Ti (above 1% ) and their impact on mechanical properties. Saud et al. [6-7] considered the impact of small amounts of alloying components such Co and Fe (below 1%) on the structure and properties of Cu-based SMA composites.
2.Experimental Work 2.1.Materials and procedures Pure Cu (99.99% purity) wires, Al (99.99% purity) foils, and Ni (99.99% purity) powder were melted in a vacuum induction furnace under an argon atmosphere at 1200 °C, and then, the melt was poured into a cylindrical alloy steel die (1.4 cm in diameter). Then, it was re-melted and 0.3%, 1.0%, 3.0% Sn was added and stirred at 1100°C. Homogenization was carried out at 900 ° C for 30 min and then the samples were quenched in an iced brine(90%H2O-10%NaCl) solution. Then, they were wire cut into specimens with 0.5 cm height for SEM, DSC, and XRD measurements. The chemical compositions of the as-cast and homogenized specimens are listed in Table 1. Table 1 Chemical Composition of SMA
Alloy
Te%
Al%
Ni%
Base SMA
---
14
4.5
Cu% Rem
T1 T2 T3
0.3 1 3
14 14 14
4.5 4.5 4.5
Rem Rem Rem
.
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R.S.A. Adnan / Materials Today: Proceedings 18 (2019) 2242–2249
2.2 XRD and SEM –Optical Microscope
XRD was performed by using Shimadzu 3000 XRD EDX Instrument Cu Target Cu(α) λ=1.45 A°,Then, the grain size was calculated using the Debye---Scherrer equation [4]. 0.9λ (1) D= B / Cos Θ where λ is the wavelength of the X-ray (Cu Kα radiation), B is the peak full width at half maximum, and θ is the Bragg angle. For the microstructure examination, the specimens were ground and polished and etched in a solution that consists of FeCl3·6H2O + HCl + methanol, and then, examination was performed using for 4 min and then microstructure by Kruss optical microscopy & Tescan easy probe SEM –with attached Oxford EDS 2.3 DSC Test DSC was preformed using SATRAN Lab-SYS 300 with a range of 25—250 °C) in both directions exothermic and endothermic result were exported to Microsoft EXCEL to calculate the equilibrium temperature using equation (1) [1]. °=
(
+
)
(2)
Results were imported into Microsoft EXCEL to calculate the enthalpy (ΔH) as the area under the curve. Then, a mathematical model was prepared to calculate the entropy (ΔS) as the free energy (ΔG), as shown in equation (4) [5] ∆ ∆ = (3) (4) ∆ =∆ − ∆ After the measurements, the specific heat capacity values were calculated using the SATRAN LabSYS 300 Device Data by applying; (dQ/dt) is the heat flux given by the DSC curve, m is the mass of sample, (dT/dt) is the heating rate of the sample, T is the temperature, and t is the time. Then, the activation energy was calculated using the model proposed by Ozawa [4]: (log ∅) − (5) = 1/ where b is a constant (0.4567) and R is the universal gas constant. In addition, the model proposed by Kissinger [5] is as follows: -
=
.
(
/ /
)
(6)
where .. is the heating rate and Tm is the maximum temperature of the DSC peak [5]. 3.Results and Discussions The XRD results shown in Figures (1), (2), (3), and (4) indicate the main AlCu3 phase and Al7Cu23Ni. There is a shift in the chart with the increase in the Te content. The formation of an intermetallic compound, the stabilization of the β` and γ` phase, and the increase in the intensity from 4000 to 8000 CPS indicate that the shifting is due to the addition of Te[8]
R.S.A. Adnan / Materials Today: Proceedings 18 (2019) 2242–2249
Fig 1 XRD results for base SMA
Fig .3 XRD results for T2 SMA
2245
Fig .2 XRD results for T1 SMA
Fig .4 XRD results for T3
3.2 SEM and Optical Microscopy SEM images showed both stacked piles in pairs or Four piles martensite (γ`) and the needle-like martensite (β`). The Te particles were non-homogenously distributed in the matrix. With the increase in the Te content, the β Phase is restrained be the distribution of the Sn grains, in particular the smaller size martensite in manner similar to Saud et.al[9] concluded in the use of B particles also it also restrained the martensite phases. EDS results shown in Figure (5) (6) confirmed the chemical composition of the alloys. Figure (7) (8) and Figure (9) shows the Debye-Scherrer equation results: a slight increase in the grain size with increasing Te content during homogenization because of the limited function of Homogenization Treatment .
Fig 5 SEM and optical microscopy image of base SMA
Fig 6 Optical microscopy image of T1 Alloy
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R.S.A. Adnan / Materials Today: Proceedings 18 (2019) 2242–2249
Fig 7 SEM and optical microscopy image of T2 SMA
Fig 8 SEM and optical microscopy image of T3 Alloy
Fig. 9 EDS results for T3 alloy
Fig. 10 Debye–Scherrer equation results
R.S.A. Adnan / Materials Today: Proceedings 18 (2019) 2242–2249
2247
3.3 DSC Results Table (2) shows the shape memory properties; it shows an increase in the transformation temperature in figures (10,11,12, and 13 ) shows DSC curves of base and Te added SMAs the domain is in range and also the peak level is less as similar behavior as Ti in small amounts[9], the case of T1 above the domain (100-170) °C Due to the effect of Te addition while in T2 Alloy there is a limited shifting in the case of the end transformation temperature Mf and Af Due to the Te effect was halted by the γ ` phase is more dominating than β ` phase,with an increase in the equilibrium temperature as shown in figures(10),(11),(12) and (13) ,(14) respectively[8]. Also, the peak temperature increased in the endothermic direction, while it decreased in the exothermic direction, which were in agreement with the results of Adnan et al. [7]. Table (2) Shape memory effect results Alloy\Temperature
As°C
Af°C
Ms°C
Mf°C
T°
Ap°C
Mp°C
SMA
129
165
133
100
149
144
110
T1
215
242
109
92
176
230
109
T2 T3
181 150
199 186
129 165
76 127
165 176
190 170
100 150
Fig (11) Thermogram of base SMA
Fig (13) Thermogram of T2 SMA
Fig(12) Thermogram of T1 SMA
Fig(14) Thermogram of T3 SMA
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R.S.A. Adnan / Materials Today: Proceedings 18 (2019) 2242–2249
The results were exported into Microsoft EXCEL. Equations 1–6 were applied to calculate the enthalpy (ΔH), entropy (ΔS), and free energy (ΔG) for the base alloys with the addition of Te after calculating (ΔH) by means of area under the curve and substituting equation 3 into equation 6 to calculate the entropy and activation energy. Results are shown in Tables 3 and 4. The results show an increase in the enthalpy and decrease in the entropy in the exothermic direction with an increase in the Sn content, and a decrease in the Enthalpy and Entropy in the endothermic direction this is a result to the addition of Te .As for the case of the results of the activation Te Addition showed a decrease in activation energy that the thermo-mechanical transformation is less required while with the increase of maximum temperature and equilibrium temperature , Te is a High melting point element so with this characterization the energy is lowered more with Te Increase of percentage.in both equations The transformation of the SMAs is related to the energy which the materials retain in their structure. Therefore, this energy consists of the chemical energy and reversible mechanical energy and T is the temperature at which the chemical energies of austenite and martensite phases are equal [7] Table .3 Results of mathematical modelling for thermal properties of SMA Alloy
ΔH M-A /J·g-1
ΔH A-M /J·g-1
ΔSM-A /J·g-1 C°-1
ΔSA-M /J·g-1 C°-1
SMA
1.9
-2.54
0.12
-0.17
T1
3.375
-2.9
0.022
-0.019
T2
8.025
-6
0.045
-0.036
T3
32.5
-15
0.184
-0.085
The activation energies were calculated for the reverse transformation according to Kissinger and Ozawa methods and are given in Table 4. The activation energy decreased with increased Te content; these results agree with the results reported by Ahmed Adnan et al. [7]. Table. 4 Activation energy for the base and SMA alloys with Te Alloy
T°C
Ea(j)
Eb(j)
Base
149
-22.5661
-21.1182
T1
176
-25.81623
-24.8113
T2
165
-23.68461
-22.0784
T2
176
-35.52692
-29.4834
R.S.A. Adnan / Materials Today: Proceedings 18 (2019) 2242–2249
2249
The specific heat readings obtained from the DSC device showed a decrease in the exothermic direction with a decrease in both direction exothermic and endothermic with an slight increase in the Specific heat at 0.3% Te it’s unexplainable as show in below fig 15.
Fig .15 Relationship between specific heat and Te content
4. Conclusions 1. With Te addition, the transformation temperature shifted for the base alloy and the equilibrium temperature increased. 2. Te particles were non-homogenously distributed in the matrix. This restricted martensite growth in the matrix. 3. The addition of Te increased the enthalpy of the shape memory alloys and decreased the entropy in the exothermic direction and vice versa. 4. Te Addition lowered the activation energy as per both Ozawa and Kissinger equations in the exothermic direction. 5. Te addition lowered the specific heat (Cp) of the SMA in most cases. 6. Te Addition with homogenization increased the grain size. Acknowledgements The author would like to thank the staff of the XRD Laboratory in the Nano Technology Center, the DSC Laboratory in the Department of Materials Engineering, SEM-ESD Laboratory in the Department of Production Engineering and Metallurgy at The University of Technology-Iraq. References [1] L’excellent Christian 2007 Shape Memory Alloy Handbook (New York: John Wiley and Son), P. 2 [2] J.J. Mohd, M. Leary, and A. Sibic, Materials and Design, 56, 6, 2014 [3] A. Agrawal and R.K. Dube, Journal of Alloys and Compounds, 750, 235-247, 2018 [4] Z. Karagoz and C. Aksu Canbay, Thermal Analysis Calorimetry, 114, 1069-1074, 2013 [5] C. Aksu Canbay and C,Z. Karagoz, International Journal Thermophysics, 34, 1325-1335, 2013 [6] I.N. Qader, M. Kok, and F. Dağdelen, Physica B: Physics of Condensed Matter, 2018 [7] R.S.Ahmed Adnan and M.M. Abudlbakki “The effect of Sn addition on Transformation Temperature and Thermal Properties of Cu-Al-Ni Shape m emory alloy”,IOP Conference Series: Materials Science and Engineering, 454 ,1, 12050,2018) [8] M.K. Abbass, M.M. Radhy, R.S.A. Adnan, International Journal of Advances in Science, Engineering and Technology(IJASEAT), 4,2, 161164, 2016 [9] S. Saud. ,E. Hamza T. Abubakar T, M.K.Ibrahim.,A. Bahador, Metallurgical and Materials Transactions A , 47A, 8 2016 s. Research , 30,14,2015