CoCrFeNi Yüksek Entropili Alaşımların Nitrürleme Davranışı Üzerinde Hf İlavesinin Etkisi

Öz

Bu çalışmada, nitrürleme işleminin CoCrFeNiHf₀,₁–₀,₄₂ yüksek entropili alaşımlar üzerindeki etkisi ve iyileştirmeleri incelenmiştir. CoCrFeNiHfₓ alaşımına eklenen Hf oranı artırıldığında, alaşımların yapısı kademeli olarak tek fazlı FCC'den önce Ni₇Hf₂ + FCC’ye, sonrasında ise C15 Laves ve FCC fazlarına dönüşmüştür. Nitrürleme işlemi sonucunda bir nitrür tabakası (NL) oluşmuştur. Alaşımlardaki Hf oranının artırılması başlangıçta birleşik tabaka kalınlığının artmasıyla sonuçlanmıştır. Öte yandan, NL kalınlığı, (CoCrFeNi)₉₀,₅(Hf)₉,₅ bileşiminde azalmıştır. Bu kalınlıklar sırasıyla (CoCrFeNi)₉₇,₆(Hf)₂,₄ için 23 µm, (CoCrFeNi)₉₅,₂₅(Hf)₄,₇₅ için 28 µm ve (CoCrFeNi)₉₀,₅(Hf)₉,₅ için 25 µm olarak belirlenmiştir. Ayrıca, Hf miktarına bağlı olarak sertlik değişimi değerlendirildiğinde; yapılan ölçümler sonucunda Hf elementinin artışıyla alaşımın sertliğinde doğrudan bir artış elde edildiği belirlenmiştir.

Anahtar Kelimeler

• Yüksek Entropili Alaşımlar
• Nitrürleme
• Laves Fazı
• Yüzey Sertleştirme

Proje Numarası

GTU BAP 2022-A-101-11

The Effect of Hf Addition on the Nitriding Behavior of CoCrFeNi High Entropy Alloys

Öz

The effect and improvements of nitriding process on CoCrFeNiHf0,1-0,42 high entropy alloys were investigated in this study. When raising the ratio of added Hf in CoCrFeNiHfx, the structure of the alloys progressively transformed from single phase FCC to initially Ni7Hf2 + FCC and lastly to C15 Laves and FCC phases. The nitriding process concluded the formation nitride layer (NL). Raising the ratio of Hf in the alloys concluded in increased at first the combined layer thickness. On the other hand, NL thickness diminished when the composition (CoCrFeNi)90,5(Hf)9,5 which were determined for (CoCrFeNi)97,6(Hf)2,4, (CoCrFeNi)95,25(Hf)4,75, (CoCrFeNi)90,5(Hf)9,5 to be 23 µm, 28 µm, 25 µm respectively. Moreover, considering the hardness change, depending on the amount of Hf added; it was determined because of the measurements that a direct increase in the hardness of the alloy was obtained with the increasing Hf element.

Anahtar Kelimeler

• High entropy alloy
• Nitriding
• Laves phase
• Surface hardening

Destekleyen Kurum

Gebze Technical University

Proje Numarası

GTU BAP 2022-A-101-11

Etik Beyan

This study was funded by Gebze Technical University (Project Number: 2022-A-101-11) and represents a portion of the MSc thesis of Dogancan CEYLAN.

Teşekkür

The authors would like to thank technicians Ahmet Nazim and Adem Sen for their assistance with SEM, SEM-EDS, and XRD analysis.

Kaynakça

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