Particle-Level Engineering of Cu-Al-Ni Shape Memory Alloy Powders via Cryogenic Milling and Electroless Ni Coating
METALS, cilt.16, sa.5, 2026 (SCI-Expanded, Scopus)
- Yayın Türü: Makale / Tam Makale
- Cilt numarası: 16 Sayı: 5
- Basım Tarihi: 2026
- Doi Numarası: 10.3390/met16050529
- Dergi Adı: METALS
- Derginin Tarandığı İndeksler: Science Citation Index Expanded (SCI-EXPANDED), Scopus, Applied Science & Technology Source, Compendex, INSPEC, Directory of Open Access Journals, Materials Science & Engineering Collection (ProQuest), Technology Collection (ProQuest)
- Karadeniz Teknik Üniversitesi Adresli: Evet
Özet
At particle-level engineering, this study mainly focused on the issues of microstructural heterogeneity and the high oxidation susceptibility of Cu-Al-Ni shape memory alloys (SMAs) suitable for high-temperature actuation. Initial powders of Cu (82-83 wt.%) and Al (14-15 wt.%) were first milled mechanically and the Cu-Al particles were modified using an electroless Nickel (Ni) coating process to achieve a controlled Ni enrichment of 4-5 wt.%. The SEM-EDS, XRD, and TGA findings reveal that the cryogenic milling effectively reforms dendritic Cu and spherical Al particles into a refined composite structure. This process resulted in particle size reduction from 40-70 & micro;m to 5-20 & micro;m, and apparent density values increased from 3.45 g & centerdot;cm-3 to 4.10 g & centerdot;cm-3. Microstructural investigations showed that the continuous Ni layer, without generating unwanted intermetallic phases, was obtained with the help of an electroless coating process. In addition, it was confirmed that the crystallite size decreased from 52.10 nm to 41.71 nm. Additionally, the oxidation of nickel-coated and cryogenically milled powders occurred at temperatures above 350 degrees C owing to the formation of a protective surface layer. In other words, these powders exhibited higher thermal stability. Consequently, this dual processing procedure represents a very useful method for changing particle shape and interfacial composition. These combined methods can help to create a powder structure with a composition optimum for the making of high-performance Cu-Al-Ni SMAs.