Ön Alaşımlı NiTi Tozlarına Cu İlavesinin Mikroyapısal Etkileri

Öz

Bu çalışmada, (NiTi)95Cu5 ağırlıkça % alaşım tozları, ön-alaşımlı NiTi tozuna Cu ilavesi yapılarak 60, 120 ve 180 dakika sürelerle mekanik alaşımlama yöntemiyle üretilmiştir. Öğütme süresinin morfoloji, elementel dağılım, partikül boyutu ve faz evrimi üzerindeki etkileri sistematik olarak incelenmiştir. Tozlar SEM, EDS, partikül boyut analizi ve XRD teknikleri kullanılarak karakterize edildi. SEM gözlemleri, tozların genel olarak küresel bir morfolojiyi koruduğunu, ancak daha uzun öğütme süreleriyle yüzey deformasyonu ve aglomerasyonun arttığını ortaya koymuştur. EDS sonuçları, tüm numunelerde Ni, Ti ve Cu elementlerinin varlığını doğruladı ve öğütme süresi arttıkça Cu dağılımının daha homojen hale geldiğini göstermiştir. Partikül boyut analizi, ortalama partikül boyutunun belirgin biçimde azalmadığını, ancak boyut dağılımının genişlediğini ortaya koyarak, parçalanma ve soğuk kaynaklanma süreçlerinin eşzamanlı gerçekleştiğini işaret etmiştir. XRD sonuçları, NiTi, Ti(Ni,Cu), Ni4Ti3 ve Ni3Ti fazlarının varlığını gösterdi. Öğütme süresi arttıkça Ni3Ti ve Ni4Ti3 fazlarının şiddetleri azalırken NiTiCu katı çözeltisinin kararlılığı iyileştiği gözlenmiştir. Genel olarak, mekanik alaşımlama süresinin, Cu ile modifiye edilmiş NiTi’de faz kararlılığını, elementel homojenliği ve partikül morfolojisini kontrol etmede belirleyici bir rol oynadığı bulunmuştur.

Anahtar Kelimeler

• Mekanik Alaşımlama
• Şekil Hafızalı Alaşım
• NiTi
• Toz Metalurjisi
• Cu İlavesi.

Microstructural Effects of Cu Addition to Pre-Alloyed NiTi Powders

Öz

In this study, (NiTi)95Cu5 wt.% alloy powders were produced by mechanical alloying of pre-alloyed NiTi powder with Cu addition for 60, 120, and 180 minutes. The effects of milling duration on the morphology, elemental distribution, particle size, and phase evolution were systematically investigated. The powders were characterized using SEM, EDS, particle size analysis, and XRD techniques. SEM observations revealed that the powders maintained a generally spherical morphology, while surface deformation and agglomeration increased with longer milling times. EDS results confirmed the presence of Ni, Ti, and Cu elements in all samples, with Cu distribution becoming more homogeneous as the milling time increased. Particle size analysis indicated that the average particle size did not decrease significantly, but the size distribution became broader, suggesting simultaneous fragmentation and cold welding processes. XRD results showed the presence of NiTi, Ti(Ni,Cu), Ni4Ti3, and Ni3Ti phases. With increasing milling time, the intensities of Ni3Ti and Ni4Ti3 phases decreased, while the stability of the NiTiCu solid solution improved. Overall, mechanical alloying time was found to play a decisive role in controlling phase stability, elemental homogeneity, and particle morphology in Cu-modified NiTi.

Anahtar Kelimeler

• Mechanical alloying
• Shape memory alloy
• NiTi
• Powder metallurgy
• Cu addition.

Kaynakça

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