Bakır ve Magnezyum Katkılarının Al-17Si Alaşımının Yapısal, Mekanik ve Tribolojik Özelliklerine Etkisi

Year 2019, Volume: 11 Issue: 2, 685 - 694, 30.06.2019

Ali Paşa Hekimoğlu , Murat Hacıosmanoğlu

https://doi.org/10.29137/umagd.546562

Cited By: 2

Abstract

İkili Al-17Si, üçlü
Al-17Si-4Cu ve dörtlü Al-17Si-4Cu-0,6Mg alaşımları kokil kalıba döküm
yöntemiyle üretildi. Üretilen alaşımların kimyasal bileşimleri spark optik
emisyon spektrometresi (Spark OES) yöntemi ile belirlenerek doğrulandı. İçyapı
incelemeleri standart metalografik yöntemlerle hazırlanan numuneler üzerinde
ışık ve taramalı elektron mikroskobu (SEM) ile gerçekleştirildi. Alaşımların
sertliği Brinell sertlik ölçme yöntemiyle, akma ve çekme dayanımı ile kopma
uzaması değerleri ise üniversal bir test makinesinde yapılan çekme deneyleri
ile belirlendi. Çekme deneylerine tabi tutulan numunelerin yüzeyleri ve yüzey
altları SEM’de incelenerek görüntülendi. Alaşımların tribolojik özellikleri bilye
disk esaslı bir deney düzeneği yardımıyla belirlendi. Al-17Si alaşımının
içyapısının alüminyumca zengin α, ötektik Al-Si, primer silisyum ve β
fazlarından, üçlü Al-17Si-4Cu alaşımının Al-17Si alaşımındaki fazların yanı
sıra bakırca zengin θ (CuAl₂) fazını da içerdiği görüldü. Dörtlü Al-17Si-4Cu-0,6Mg
alaşımında ise üçlü Al-17Si-4Cu alaşımındaki fazlara ilave olarak Mg₂Si
fazının oluştuğu ve ayrıca ikili ve üçlü alaşımda görülen β fazının dörtlü
alaşımda π fazına dönüştüğü belirlendi. Bakır ve magnezyum katkılarının
incelenen alaşımların sertlik, akma ve çekme dayanımı ile birlikte aşınma
direncini arttırdığı, kopma uzaması değerlerini ise düşürdüğü gözlendi. Mekanik
ve tribolojik deneylerden elde edilen sonuçlar alaşımların yapısal
özelliklerine dayandırılarak irdelendi.

Keywords

Al-17Si esaslı alaşımlar, İçyapı, Mekanik özellikler, Aşınma, Kırılma

Effect of Copper and Magnesium Additions on the Structural, Mechanical and Tribological Properties of the Al-17Si Alloy

Abstract

Binary Al-17Si, ternary Al-17Si-4Cu and quaternary
Al-17Si-4Cu-0.6Mg alloys were produced by permanent mold casting method. Chemical
composition of the produced alloys was confirmed by spark optical emission
spectrometry (Spark OES) method. Structural examinations of the alloys were
carried out with optical and scanning electron microscopy (SEM) on the samples
prepared by standard metallographic methods. The hardness of the alloys was
determined by the Brinell hardness measurement method. The hardness of the
alloys was determined by the Brinell hardness measurement method. The values of
the elongation to fracture, yield and tensile strength of the alloys produced
were determined by tensile tests performed with a universal testing machine. The
fracture surfaces and the sub-surfaces of the tensile test samples were
examined by SEM. Tribological characteristics of the alloys were investigated
by a ball-on-disc type friction-wear test machine. It was observed that
microstructure of the Al-17Si alloy consisted of the phases of aluminum-rich α,
eutectic Al-Si, primary silicon and β. Ternary Al-17Si-4Cu alloy showed a
microstructure consisting of the phase of θ(CuAl₂) in addition to
phases observed in the Al-17Si alloy. Al-17Si-4Cu-0,6Mg alloy showed a
microstructure consisting of Mg2Si in the addition to the phases observed in
the ternary alloy. In addition to this the β phase observed in the ternary
alloy turned into π phase in the quaternary alloy. Copper and magnesium additions
resulted in an increase in the wear resistance, hardness, yield and tensile
strength of the alloys tested, but a decrease in the elongation to fracture. The
results obtained from mechanical and tribological tests were discussed on the
basis of structural changes observed in the alloys due to copper and magnesium
additions.

Keywords

Al-17Si based alloys, Microstructure, Mechanical properties, Wear, Fracture

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