Mekanik alaşımlama ile üretilen nanokristal yapılı östenitik paslanmaz çelik alaşımlarında Y ve nano - Y2O3 ilavelerinin tane büyümesi ve sertliğe etkisi

Yıl 2019, Cilt: 34 Sayı: 3, 1265 - 1272, 29.05.2019

Hasan Kotan

https://doi.org/10.17341/gazimmfd.460523

Cited By: 1

Öz

Bu çalışmada, Fe₇₄Cr₁₈Ni₈ paslanmaz çelik alaşımı Y elementi ve nano boyutta Y₂O₃ ilaveleri ile mekanik alaşımlama yöntemi kullanılarak nanokristal yapıda üretilmiş ve 1100 ºC’ye kadar farklı sıcaklıklarda tavlama işlemine tabii tutulmuştur. X-ışınları kırınımı, geçirimli elektron mikroskobu ve odaklanmış iyon demeti mikroskobu kullanılarak sıcaklığa bağlı olarak mikroyapıda meydana gelen değişimler incelenmiştir. Mikroyapının malzeme sertliğine etkisinden faydalanılarak tavlama sıcaklığına bağlı olarak mekanik özelliklerdeki değişimler tespit edilmiştir. Elde edilen sonuçlar denge durumunda ymk kafes yapısına sahip olan bu paslanmaz çelik kristal yapılarının mekanik alaşımlama sırasındaki yoğun plastik deformasyondan dolayı hmk kafes yapısındaki a’ – martenzite dönüştüğünü göstermektedir. Mekanik alaşımlamadan sonra uygulanan tavlama işlemi ile sıcaklığa bağlı olarak farklı oranlarda martenzit – östenit tersine faz dönüşümünün gerçekleştiği tespit edilmiştir. Nanokristal yapılı Fe₇₄Cr₁₈Ni₈ paslanmaz çelik alaşımında yüksek tane sınırı alanından dolayı yüksek sıcaklıklarda meydana gelen ve mikrometre seviyelerine ulaşan tane boyutunun, Y ve Y₂O₃ ilaveleri ile 1100 °C’de yapılan tavlamadan sonra bile yaklaşık olarak 150 nm seviyesinde tutulduğu ve sertliğinin ise 6,5 GPa seviyelerinde korunduğu tespit edilmiştir.

Anahtar Kelimeler

paslanmaz çelikler, tane büyümesi; faz dönüşümü; mekanik alaşımlama; sertlik

Kaynakça

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