Home
Resources
Publications
Characteristics of Martensitic and Strain-Glass Transitions of the Fe-substituted TiNi Shape Memory Alloys Probed by Transport and Thermal Measurements

Characteristics of Martensitic and Strain-Glass Transitions of the Fe-substituted TiNi Shape Memory Alloys Probed by Transport and Thermal Measurements

Balakrishnan Ramachandran, Pei-Chi Chang, Yung-Kang Kuo, Chen Chien, Shyi-Kaan Wu

Sci Rep. 2017 Nov 27;7(1):16336.

PMID: 29180627

Abstract:

The electrical resistivity, Seebeck coefficient, thermal conductivity, and specific heat of Ti50Ni50-x Fe x (x = 2.0-10.0 at.%) shape memory alloys (SMAs) were measured to investigate the influence of point defects (Fe) on the martensitic transformation characteristics. Our results show that the Ti50Ni48Fe2 and Ti50Ni47Fe3 SMAs have a two-step martensitic transformation (B2 → R and R → B19'), while the Ti50Ni46Fe4, Ti50Ni44.5Fe5.5, and Ti50Ni44Fe6 SMAs display a one-step martensitic transition (B2 → R). However, the compounds Ti50Ni42Fe8 and Ti50Ni40Fe10 show strain glass features (frozen strain-ordered state). Importantly, the induced point defects significantly alter the martensitic transformation characteristics, namely transition temperature and width of thermal hysteresis during the transition. This can be explained by the stabilization of austenite B2 phase upon Fe substitution, which ultimately leads to the decrease in enthalpy that associated to the martensitic transition. To determine the boundary composition that separates the R-phase and strain glass systems in this series of SMAs, a Ni-rich specimen Ti49Ni45Fe6 was fabricated. Remarkably, a slight change in Ti/Ni ratio converts Ti49Ni45Fe6 SMA into a strain glass system. Overall, the evolution of phase transformation in the Fe-substituted TiNi SMAs is presumably caused by the changes in local lattice structure via the induced local strain fields by Fe point defects.

Chemicals Related in the Paper:

Catalog Number	Product Name	Structure	CAS Number	Price
AP1884640996	NI-42		1884640-99-6	Price

As a specialist in analytical chemical Products, Alfa Chemistry offers consumers a wealth of raw materials and a full range of technologies and services.

QUICK LINKS

HEADQUARTERS

Tel:

Fax:

Email: