TY  - JOUR
T2  - Journal of Mining and Metallurgy, Section B: Metallurgy
TI  - Influence of heat treatment on the microstructure, phase transformation, and thermal cycling stability of NiTiZr alloys
VL  - 62
IS  - 2
SP  - 243
EP  - 255
PY  - 2026
DA  - 14 September 2026
DO  - 10.2298/JMMB260306018Y
UR  - https://doi.org/10.2298/JMMB260306018Y
AU  - Yu, Qiang
AU  - Rizawanguli
AU  - Qi, Pengfei
AU  - Gong, Ruixin
AU  - Zhang, Qian
AU  - Qu, Wentao
AD  - a School of Intelligent Transportation, Xinjiang Vocational University, Urumqi, China; b College of Petroleum Engineering, Xi'an Petroleum University Engineering Research Center of Safety and Energy Saving in Oil & Gas Storage and Transportation, Universities of Shaanxi Province, China; c School of Mechanical Engineering, Xi'an Petroleum University, Xi'an, Shaanxi, China;
AB  - This work examines how  post-annealing temperature affects the thermal-energy storage behavior of the Ni49.5Ti38.5Zr12 phase-change alloy, with the aim of mitigating heat loss and electronic failures that often occur in insulation bottles due to structural imperfections or inadequate heat-storage capability. Specimens were heat-treated over a range of temperatures, and their transformation characteristics, microstructural evolution, and thermophysical performance were systematically evaluated. The results indicate that with increasing heat-treatment temperature, the transformation enthalpy rises initially and then declines. This trend is associated with the progressive morphological change of the precipitated ?1 phase-from fine bubble-like features to sheet-like structures-together with a grain size variation that also increases first and subsequently decreases. In addition, thermal conductivity shows an overall upward tendency, which can be explained by enhanced atomic motion in the crystal lattice at elevated temperatures. After annealing at 600 °C, the alloy exhibits a transformation enthalpy of 29.8 J·g-1, a transformation start temperature (As) of 72.97 °C, a finish temperature (Af) of 119.81°C, a thermal conductivity of 15.3 W·g-1·K-1, and a microhardness of 355.147 HV. Moreover, the material retains good thermal stability after repeated thermal cycling. These outcomes provide theoretical support for employing NiTiZr-based materials in downhole insulation bottles. An annealing window of 500-700 °C is recommended to improve transformation stability and thermophysical properties, enabling suitability for high-temperature service environments such as downhole tools in the petroleum industry.
KW  - NiTiZr alloy
KW  - Heat treatment
KW  - Microstructure Phase change characteristics
KW  - Thermal cycling stability
N1  - Correspondence Address: Wentao Qu; School of Mechanical Engineering, Xi'an Petroleum University, Xi'an, Shaanxi, China; email: wtqu@xsyu.edu.cn
N1  - J. Min. Metall. Sect. B-Metall., 62 (2) (2026) 243-255. doi:10.2298/JMMB260306018Y
PB  - Technical Faculty in Bor
SN  - 1450-5339 (ISSN)
LA  - English
J2  - J. Min. Metall. Sect. B Metall.
M3  - Article
ER  -