AZ91 Mg Alaşımına Farklı Oranlarda Sb İlavesi İle Katılaşma Hızının Mikroyapı ve Mekanik Özelliklere Etkisi

Mevcut kullanım alanları gün geçtikçe artış gösteren Mg alaşımlarının, teknolojik gelişmelere uyum sağlayabilmesi için mekanik özellikler bakımından daha fazla geliştirilmesi gerekliliği ortaya çıkmıştır. Günümüzde çözünebilir biyo-malzeme olarak sağlık alanında da kullanılmaya başlayan Mg ve alaşımlarına kazandırılan fiziksel ve mekanik özellikler malzemenin kullanım ömrünü tayin etmektedir. Dolayısıyla bu çalışmada, AZ91 serisi Mg alaşımına farklı oranlarda (%0.2 - %0.5 ve %1.0) Sb elementi ilavesi ve katılaşma hızının da etkisiyle mekanik özelliklerinin geliştirilmesi amaçlanmıştır. Yapılan çalışmanın neticesinde sonuçlar incelendiğinde; AZ91 alaşımının genel olarak tane yapısının α-Mg ve tane sınırları boyunca yayılan β-Mg17Al12 fazından oluştuğu saptanmıştır. Hızlı soğumanın tane yapısında küçülmelere sebep olduğu bununla birlikte tane sınırlarında bulunan Mg17Al12 intermetalik fazının incelip parçalandığı tespit edilmiştir. Tespit edilen bu etkilerin neticesinde de alaşımın çekme, akma ve uzama değerlerinde artışın olduğu gözlenmiştir. Bununla birlikte AZ91 alaşımına ilave edilen Sb ile yapıda Mg3Sb2 fazı oluşmuştur. Bu intermetalik fazın yapıda meydana getirdiği değişiklikler ile alaşımın mekanik özelliklerinde artış izlenmiştir. AZ91 alaşımının çekme dayanımı Sb ilavesi ile 163 MPa seviyelerinden 217 MPa seviyelerine kadar iyileşmiştir. Sb ilavesiyle AZ91 alaşımında sertlik değerleri yaklaşık 57 HV değerlerinden 81 HV değerlerine yükselmiştir.

Anahtar Kelimeler:

AZ91, Mg alaşımları, soğuma hızı, mekanik özellikler, mikroyapı

Effects of Solidification Rate on Microstructure and Mechanical Properties with Sb at Different Ratio of AZ91 Quality Mg Alloy

The increasing use of Mg alloys in today's applications has necessitated further improvement in mechanical properties in order to adapt to technological developments. The physical and mechanical properties of Mg and its alloys, which are now being used in the field of health as soluble biomaterials, determine the useful life of the material. Therefore, in this study, it was aimed to improve the mechanical properties of AZ91 series Mg alloy at different ratios (0.2% - 0.5% and 1.0%) by the addition of Sb element and the effect of solidification rate. When the results of the study are examined, it has been found that the AZ91 alloy generally consists of α-Mg grain structure and β-Mg17Al12 phase extending along grain boundaries. It has been found that the intermetallic phase of Mg17Al12 in the grain boundaries has been thinned and disintegrated because of rapid cooling causing the grain structure to shrink. As a result of these detected effects, it was observed that the tensile strength of the alloy, the yield strength and the unit (percent) elongation ratios were increased. However, Mg3Sb2 phase was formed with Sb added to AZ91 alloy. The mechanical properties of the alloy increased with the changes in the structure of this intermetallic phase. The tensile strength of the AZ91 alloy improved with the addition of Sb from 163 MPa to 217 MPa and with the increasing amount of Sb, the hardness values of the AZ91 alloy increased from about 57 HV to 81 HV.

Keywords:

AZ91 Mg alloys, cooling rate, mechanical properties, , microstructure,

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