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

Year 2019, Volume: 11 Issue: 2, 451 - 463, 30.06.2019

Levent Elen , Yunus Türen , Erkan Koç

https://doi.org/10.29137/umagd.507264

Cited By: 6

Abstract

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.

Keywords

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

Abstract

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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