Mekanik Alaşımla Süresince Al85Co7Y8 Alaşımının Faz Değişimi

Abstract

Bu çalışmada nanoyapılı Al₈₅Co₇Y₈ (at.%) alaşımı, mekanik alaşımlama (MA) tekniği kullanılarak elemental tozların katı hal reaksiyonuyla sentezlenmiştir. Toz alaşımlar, argon gazı altında sertleştirilmiş paslanmaz çelik hazne ve bilyeler kullanılarak yüksek-enerjili bilyeli değirmen içerisinde 300 saatlik öğütme işlemine tabi tutulmuştur. Öğütme işlemi süresince numunelerdeki yapısal ve morfolojik değişimler X-ışını difraksiyonu (XRD) ve taramalı elektron mikroskobu (SEM) ile termal kararlılıkları ise diferansiyel termal analiz (DTA) ile incelenmiştir. MA işlemi sonucunda aşırı doymuş fcc-Al katı çözelti fazı içeren alaşımlar üretilmiştir. Al₈₅Co₇Y₈ alaşımının 300 saatlik öğütme işlemi sonrasındaki kristalit boyutu yaklaşık 16 nm olarak bulunmuştur.

Keywords

• Al-Co-Y alaşımı,Nanokristal alaşım,Mekanik alaşımlama,Faz değişimi

Phase Evolution of Al85Co7Y8 Alloy during Mechanical Alloying

Abstract

In this study, the nanostructured Al₈₅Co₇Y₈ (at.%) alloy was synthesized by a solid state reaction from the constituent elemental powder mixture via mechanical alloying (MA). The powder mixture was ball milled for times up to 300 h in a planetary high energy mill using hardened steel media under argon atmosphere. Structural and morphological changes during the milling process were characterized by a combination of X-ray diffraction (XRD) and scanning electron microscopy (SEM) techniques. Thermal stability of the milled powders was investigated using differential thermal analysis (DTA). The results showed that supersaturated α-Al solid solution was formed in the whole content of the milled material. The mechanically alloyed Al₈₅Co₇Y₈ powder for 300 h of milling indicated the formation of fine nanoparticles with a size of about 16 nm.

Keywords

• Al-Co-Y alloy,Nanocrystalline alloy,Mechanical alloying,Phase evolution

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