Effect of Homogenization on the Transformation Temperatures and Mechanical Properties of Cu<sub>15</sub>Ni<sub>35</sub>Hf<sub>12.5</sub>Ti<sub>25</sub>Zr<sub>12.5</sub> and Cu<sub>15</sub>Ni<sub>35</sub>Hf<sub>15</sub>Ti<sub>20</sub>Zr<sub>15</sub> High-Entropy Shape Memory Alloys
The major challenge of high-temperature shape memory alloys (SMAs) is the collocation of phase transition temperatures (TTs: M<sub>s</sub>, M<sub>f</sub>, A<sub>s</sub>, A<sub>f</sub>) with the mechanical properties required for application. Previous r...
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| author | Shu-Yu Kuo Wei-Pin Kao Shan-Hsiu Chang Ting-En Shen Jien-Wei Yeh Che-Wei Tsai |
| author_facet | Shu-Yu Kuo Wei-Pin Kao Shan-Hsiu Chang Ting-En Shen Jien-Wei Yeh Che-Wei Tsai |
| author_sort | Shu-Yu Kuo |
| collection | DOAJ |
| description | The major challenge of high-temperature shape memory alloys (SMAs) is the collocation of phase transition temperatures (TTs: M<sub>s</sub>, M<sub>f</sub>, A<sub>s</sub>, A<sub>f</sub>) with the mechanical properties required for application. Previous research has shown that the addition of Hf and Zr into NiTi shape memory alloys (SMAs) increases TTs. Modulating the ratio of Hf and Zr can control the phase transformation temperature, and applying thermal treatments can also achieve the same goal. However, the influence of thermal treatments and precipitates on mechanical properties has not been widely discussed in previous studies. In this study, we prepared two different kinds of shape memory alloys and analyzed their phase transformation temperatures after homogenization. Homogenization successfully eliminated dendrites and inter-dendrites in the as-cast states, resulting in a reduction in the phase transformation temperatures. XRD patterns indicated the presence of B2 peaks in the as-homogenized states, demonstrating a decrease in phase transformation temperatures. Mechanical properties, such as elongation and hardness, were improved due to the uniform microstructures achieved after homogenization. Moreover, we discovered that different additions of Hf and Zr resulted in distinct properties. Alloys with lower Hf and Zr had lower phase transformation temperatures, followed by higher fracture stress and elongation. |
| first_indexed | 2024-03-11T04:48:01Z |
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| id | doaj.art-d19dc71abc1a4334960bed334f3770ab |
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| issn | 1996-1944 |
| language | English |
| last_indexed | 2024-03-11T04:48:01Z |
| publishDate | 2023-04-01 |
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| spelling | doaj.art-d19dc71abc1a4334960bed334f3770ab2023-11-17T20:14:56ZengMDPI AGMaterials1996-19442023-04-01168321210.3390/ma16083212Effect of Homogenization on the Transformation Temperatures and Mechanical Properties of Cu<sub>15</sub>Ni<sub>35</sub>Hf<sub>12.5</sub>Ti<sub>25</sub>Zr<sub>12.5</sub> and Cu<sub>15</sub>Ni<sub>35</sub>Hf<sub>15</sub>Ti<sub>20</sub>Zr<sub>15</sub> High-Entropy Shape Memory AlloysShu-Yu Kuo0Wei-Pin Kao1Shan-Hsiu Chang2Ting-En Shen3Jien-Wei Yeh4Che-Wei Tsai5Department of Materials Science and Engineering, National Tsing Hua University, Hsinchu 30013, TaiwanDepartment of Materials Science and Engineering, National Tsing Hua University, Hsinchu 30013, TaiwanDepartment of Materials Science and Engineering, National Tsing Hua University, Hsinchu 30013, TaiwanDepartment of Materials Science and Engineering, National Tsing Hua University, Hsinchu 30013, TaiwanDepartment of Materials Science and Engineering, National Tsing Hua University, Hsinchu 30013, TaiwanDepartment of Materials Science and Engineering, National Tsing Hua University, Hsinchu 30013, TaiwanThe major challenge of high-temperature shape memory alloys (SMAs) is the collocation of phase transition temperatures (TTs: M<sub>s</sub>, M<sub>f</sub>, A<sub>s</sub>, A<sub>f</sub>) with the mechanical properties required for application. Previous research has shown that the addition of Hf and Zr into NiTi shape memory alloys (SMAs) increases TTs. Modulating the ratio of Hf and Zr can control the phase transformation temperature, and applying thermal treatments can also achieve the same goal. However, the influence of thermal treatments and precipitates on mechanical properties has not been widely discussed in previous studies. In this study, we prepared two different kinds of shape memory alloys and analyzed their phase transformation temperatures after homogenization. Homogenization successfully eliminated dendrites and inter-dendrites in the as-cast states, resulting in a reduction in the phase transformation temperatures. XRD patterns indicated the presence of B2 peaks in the as-homogenized states, demonstrating a decrease in phase transformation temperatures. Mechanical properties, such as elongation and hardness, were improved due to the uniform microstructures achieved after homogenization. Moreover, we discovered that different additions of Hf and Zr resulted in distinct properties. Alloys with lower Hf and Zr had lower phase transformation temperatures, followed by higher fracture stress and elongation.https://www.mdpi.com/1996-1944/16/8/3212shape memory alloyhigh-entropy alloyhomogenizationmartensitic transformationNiTiHfZr |
| spellingShingle | Shu-Yu Kuo Wei-Pin Kao Shan-Hsiu Chang Ting-En Shen Jien-Wei Yeh Che-Wei Tsai Effect of Homogenization on the Transformation Temperatures and Mechanical Properties of Cu<sub>15</sub>Ni<sub>35</sub>Hf<sub>12.5</sub>Ti<sub>25</sub>Zr<sub>12.5</sub> and Cu<sub>15</sub>Ni<sub>35</sub>Hf<sub>15</sub>Ti<sub>20</sub>Zr<sub>15</sub> High-Entropy Shape Memory Alloys Materials shape memory alloy high-entropy alloy homogenization martensitic transformation NiTiHfZr |
| title | Effect of Homogenization on the Transformation Temperatures and Mechanical Properties of Cu<sub>15</sub>Ni<sub>35</sub>Hf<sub>12.5</sub>Ti<sub>25</sub>Zr<sub>12.5</sub> and Cu<sub>15</sub>Ni<sub>35</sub>Hf<sub>15</sub>Ti<sub>20</sub>Zr<sub>15</sub> High-Entropy Shape Memory Alloys |
| title_full | Effect of Homogenization on the Transformation Temperatures and Mechanical Properties of Cu<sub>15</sub>Ni<sub>35</sub>Hf<sub>12.5</sub>Ti<sub>25</sub>Zr<sub>12.5</sub> and Cu<sub>15</sub>Ni<sub>35</sub>Hf<sub>15</sub>Ti<sub>20</sub>Zr<sub>15</sub> High-Entropy Shape Memory Alloys |
| title_fullStr | Effect of Homogenization on the Transformation Temperatures and Mechanical Properties of Cu<sub>15</sub>Ni<sub>35</sub>Hf<sub>12.5</sub>Ti<sub>25</sub>Zr<sub>12.5</sub> and Cu<sub>15</sub>Ni<sub>35</sub>Hf<sub>15</sub>Ti<sub>20</sub>Zr<sub>15</sub> High-Entropy Shape Memory Alloys |
| title_full_unstemmed | Effect of Homogenization on the Transformation Temperatures and Mechanical Properties of Cu<sub>15</sub>Ni<sub>35</sub>Hf<sub>12.5</sub>Ti<sub>25</sub>Zr<sub>12.5</sub> and Cu<sub>15</sub>Ni<sub>35</sub>Hf<sub>15</sub>Ti<sub>20</sub>Zr<sub>15</sub> High-Entropy Shape Memory Alloys |
| title_short | Effect of Homogenization on the Transformation Temperatures and Mechanical Properties of Cu<sub>15</sub>Ni<sub>35</sub>Hf<sub>12.5</sub>Ti<sub>25</sub>Zr<sub>12.5</sub> and Cu<sub>15</sub>Ni<sub>35</sub>Hf<sub>15</sub>Ti<sub>20</sub>Zr<sub>15</sub> High-Entropy Shape Memory Alloys |
| title_sort | effect of homogenization on the transformation temperatures and mechanical properties of cu sub 15 sub ni sub 35 sub hf sub 12 5 sub ti sub 25 sub zr sub 12 5 sub and cu sub 15 sub ni sub 35 sub hf sub 15 sub ti sub 20 sub zr sub 15 sub high entropy shape memory alloys |
| topic | shape memory alloy high-entropy alloy homogenization martensitic transformation NiTiHfZr |
| url | https://www.mdpi.com/1996-1944/16/8/3212 |
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