Martensitic Transformation Behaviors of Compositionally Graded Ti–Ni-Based Shape Memory Alloys

2020 ◽  
Vol 12 (10) ◽  
pp. 1586-1590
Author(s):  
Yeon-Wook Kim ◽  
Tae-Hyun Nam ◽  
Seong-Min Lee

In this study, we demonstrate a simple and effective way to fabricate functionally graded TiNi-based alloys with linear variations of composition and martensitic transformation behavior. Ti50Ni50 and Ti50Ni35Cu15 alloy strips were fabricated through a melt overflow process. The compositionally graded diffusion couple was fabricated by annealing two strips of different alloy compositions after being placed face to face in a pressing graphite mold. The mechanical properties and martensitic transformation behaviour of the diffusion couple were analysed by tensile test and DSC. The compositionally graded specimens exhibited unique superelastic property and wide martensitic formation temperature range. Such mechanical and thermal behaviors of the compositionally graded TiNi-based alloy offer good function and controllability for actuators.

2018 ◽  
Vol 6 (19) ◽  
pp. 5228-5238 ◽  
Author(s):  
Kun Zhang ◽  
Changlong Tan ◽  
Erjun Guo ◽  
Zhicheng Feng ◽  
Jiachen Zhu ◽  
...  

A new strategy of performance tuning is proposed, which shows that replacing Sn by Cu in the Ni47Mn38Sn15−xCux magnetic shape memory alloys can simultaneously tune their martensitic transformation behavior, magnetic and mechanical properties.


Vacuum ◽  
2021 ◽  
Vol 184 ◽  
pp. 109894 ◽  
Author(s):  
Xiaoyang Yi ◽  
Haizhen Wang ◽  
Kuishan Sun ◽  
Guijuan Shen ◽  
Xianglong Meng ◽  
...  

2021 ◽  
Vol 11 (12) ◽  
pp. 5728
Author(s):  
HyeonJeong You ◽  
Minjung Kang ◽  
Sung Yi ◽  
Soongkeun Hyun ◽  
Cheolhee Kim

High-strength steels are being increasingly employed in the automotive industry, requiring efficient welding processes. This study analyzed the materials and mechanical properties of high-strength automotive steels with strengths ranging from 590 MPa to 1500 MPa, subjected to friction stir welding (FSW), which is a solid-phase welding process. The high-strength steels were hardened by a high fraction of martensite, and the welds were composed of a recrystallized zone (RZ), a partially recrystallized zone (PRZ), a tempered zone (TZ), and an unaffected base metal (BM). The RZ exhibited a higher hardness than the BM and was fully martensitic when the BM strength was 980 MPa or higher. When the BM strength was 780 MPa or higher, the PRZ and TZ softened owing to tempered martensitic formation and were the fracture locations in the tensile test, whereas BM fracture occurred in the tensile test of the 590 MPa steel weld. The joint strength, determined by the hardness and width of the softened zone, increased and then saturated with an increase in the BM strength. From the results, we can conclude that the thermal history and size of the PRZ and TZ should be controlled to enhance the joint strength of automotive steels.


2021 ◽  
Vol 804 ◽  
pp. 140777
Author(s):  
Yajiu Zhang ◽  
S. Vinodh Kumar ◽  
Wanwan Xiang ◽  
Zhigang Wu ◽  
Zuoyu Sun

Polymers ◽  
2021 ◽  
Vol 13 (7) ◽  
pp. 1137
Author(s):  
Sascha Stanic ◽  
Thomas Koch ◽  
Klaus Schmid ◽  
Simone Knaus ◽  
Vasiliki-Maria Archodoulaki

Blends of two long-chain branched polypropylenes (LCB-PP) and five linear polypropylenes (L-PP) were prepared in a single screw extruder at 240 °C. The two LCB-PPs were self-created via reactive extrusion at 180 °C by using dimyristyl peroxydicarbonate (PODIC C126) and dilauroyl peroxide (LP) as peroxides. For blending two virgin and three recycled PPs like coffee caps, yoghurt cups and buckets with different melt flow rate (MFR) values were used. The influence of using blends was assessed by investigating the rheological (dynamic and extensional rheology) and mechanical properties (tensile test and impact tensile test). The dynamic rheology indicated that the molecular weight as well as the molecular weight distribution could be increased or broadened. Also the melt strength behavior could be improved by using the two peroxide modified LCB-PP blends on the basis of PODIC C126 or PEROXAN LP (dilauroyl peroxide). In addition, the mechanical properties were consistently enhanced or at least kept constant compared to the original material. In particular, the impact tensile strength but also the elongation at break could be increased considerably. This study showed that the blending of LCB-PP can increase the investigated properties and represents a promising option, especially when using recycled PP, which demonstrates a real “up-cycling” process.


2021 ◽  
Author(s):  
Md Shajedul Hoque Thakur ◽  
Mahmudul Islam ◽  
Nur Jahan Monisha ◽  
Pritom Bose ◽  
Md. Adnan Mahathir Munshi ◽  
...  

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