Comparative phase transformation behavior of NiTiCu shape memory alloy wires following tube furnace and SiC-susceptor-assisted microwave heat treatments
JOURNAL OF THERMAL ANALYSIS AND CALORIMETRY, 2026 (SCI-Expanded, Scopus)
- Publication Type: Article / Article
- Publication Date: 2026
- Doi Number: 10.1007/s10973-026-16287-5
- Journal Name: JOURNAL OF THERMAL ANALYSIS AND CALORIMETRY
- Journal Indexes: Science Citation Index Expanded (SCI-EXPANDED), Scopus, Aerospace Database, Chemical Abstracts Core, Chimica, Compendex, Index Islamicus, INSPEC, Academic Search Ultimate (EBSCO), Engineering Source (EBSCO), Materials Science & Engineering Collection (ProQuest), Technology Collection (ProQuest)
- Dokuz Eylül University Affiliated: Yes
Abstract
NiTiCu shape memory alloy wires are attractive candidates for compact actuator and smart-material applications, but their transformation behavior is highly sensitive to the applied heat-treatment route. SiC-susceptor-assisted microwave heat treatment has mainly been explored for porous or powder-based NiTi systems, and its applicability to wire-form NiTiCu alloys, evaluated through a direct comparison with conventional tube-furnace treatment under matched temperature conditions, has not been sufficiently addressed. In this study, commercial 0.5 mm-diameter NiTiCu wires were heat-treated at 450 degrees C for 30 and 60 min in a tube furnace and for 10 and 20 min in a microwave-assisted furnace, and the resulting phase transformation behavior, room-temperature phase structure, and cross-sectional microstructure were compared by DSC, XRD, and SEM/EDS. DSC results showed that only 10 min of microwave treatment (MW-10) raised the austenite finish temperature to 44.0 degrees C and the transformation enthalpy to 4.24 J g-1, values comparable to or exceeding those obtained after 60 min in the tube furnace (Af = 40.5 degrees C, Delta HA = 3.78 J g-1), indicating that a comparable transformation response can be achieved within a substantially shorter processing time. Extending the microwave treatment to 20 min (MW-20) reversed this trend: the transformation temperatures returned close to the as-received condition (Af = - 2.1 degrees C) and the enthalpy decreased to 2.14 J g-1, revealing a pronounced sensitivity of the microwave route to holding time. XRD and SEM/EDS analyses further showed that the room-temperature phase contribution (austenite- versus martensite-related reflections) varied with treatment condition, while the Ti-Ni-dominated local composition of the cross section was preserved after both routes. These findings indicate that short-duration SiC-susceptor-assisted microwave heat treatment may offer a time-efficient route for tailoring the transformation behavior of NiTiCu wires under the investigated conditions. Furthermore, this study provides a direct experimental comparison between microwave-assisted and conventional tube-furnace heat treatments for commercial NiTiCu wire samples under the same treatment temperature, thereby addressing a gap in the current literature.