Mg-Zn-Zr Alaşımında Çökeltilerin HRTEM-EDS-SAED Çalışması

Abstract

Bu çalışmada, ekstrüde edilmiş Mg-Zn-Zr alaşımına yaşlandırma ısıl işlemi uygulanmıştır. Yaşlandırma, ekstrüzyon sonrası numuneler üzerinde 180°C'de 1-2-4-8 ve 24 saat süreyle gerçekleştirilmiştir. Yaşlanma eğrisinin elde edilmesi için mikrosertlik testleri yapılmıştır. Mikroyapıyı, ikinci fazları ve çökeltileri araştırmak için seçili alan elektron kırınımı (SAED), enerji dağılım spektrometrisi (EDS) ve yüksek çözünürlüklü geçirimli elektron mikroskobu (HRTEM) gibi ayrıntılı geçirimli elektron mikroskobu (TEM) incelemeleri kullanılmıştır. İkinci fazların ve çökeltilerin boyut, tip ve morfolojileri ileri geçirimli elektron mikroskobu teknikleri desteğiyle incelenmiştir. Sertlik sonuçları yardımı ile pik yaşlanma noktasının 8-saat yaşlanma olduğu bulunmuştur. TEM incelemeleri 8-saat yaşlanma numunesinde detaylandırılmıştır. Yaşlanma sertleşmesinden sorumlu çökeltilerin MgZn2 olduğu gözlemlenmiştir. Ayrıca bu çökeltilerim çoğu β’1 fazıdır.

Keywords

• TEM
• EDS
• SAED
• Magnezyum alaşımları
• Ekstrüzyon
• Yaşlandırma

A HRTEM-EDS-SAED Study of Precipitates in Mg-Zn-Zr Alloy

Abstract

In this study, aging heat treatment was performed on extruded Mg-Zn-Zr alloy. Aging was performed on as-extruded samples at 180°C for 1-2-4-8 and 24 hours. Microhardness tests were made to obtain the aging curve. Detailed transmission electron microscopy (TEM) examinations such as selected area electron diffraction (SAED), energy dispersive spectrometry (EDS), and high resolution transmission electron microscopy (HRTEM) were used to investigate the microstructure, second phases, and precipitates. Size, type, and morphologies of second phases and precipitates were studied aided by advanced transmission electron microscopy techniques. With the help of hardness test results peak aged condition was found to be 8 hour aging. TEM examinations were detailed for the 8-hour aged sample. It was observed that the precipitates responsible for age hardening were MgZn2. Moreover, the majority of these precipitates were β’1 phase.

Keywords

• TEM
• EDS
• SAED
• Magnesium alloys
• Extrusion
• Aging

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