Joint Addition of Zirconium, Titanium and Chromium to Commercial Pure Aluminium

Mohammed Aboraia,Hany Gad Elrab,Gomma Abdalla

doi:10.21608/jpme.2020.33579.1037

Abstract

The effect of joint addition of Zr, Ti and Cr on the grain refinement of commercial pure aluminium (99.7% Al) has been investigated by optical microscopy and scanning electron microscopy (SEM) as well as Energy Dispersive X-ray Spectroscopy (EDS). It was found that joint addition of 0.15 wt% Zr and 0.025 wt% Ti to Al can result in a remarkable refinement with an average grain size of 102 μm. It was found the optimum addition level of Ti to be 0.025 wt% in the presence of 0.1 % Zr and any increase in the Ti beyond 0.025wt% results in coarse grain size. Joint additions of 0.15 wt% Zr, 0.025 wt% Ti and 0.15 wt% Cr to Al facilitate better grain refinement and the average grain size was 75 μm. The grain refining performance of joint addition of 0.1 wt.% Zr and different additions of either Ti or Cr is higher than refining with zirconium alone. EDS and SEM analysis of the precipitated phases observed at or near the centers of the refined aluminium with joint addition of Zr and Ti was found to be Al3(Zr1-xTix). These Al3(Zr1-xTix) particles act as heterogeneous nucleation sites for α-Al during solidification and resulted in better grain refinement.

Highlights

Aluminium is the most abundant element in the earth's crust
The composition of these particles was found to fit to Al3(Zr1-xTix). These particles are to act as heterogeneous nucleation sites for Al during solidification
1- Al3(Zr1-xTix ) phase which precipitated at or near the centers of the refined grains in case of joint addition of Zr and Ti was observed by scanning electron microscopy (SEM) and confirmed by EDX

Summary

Introduction

Aluminium is the most abundant element in the earth's crust. Pure aluminium possesses many advantages to be used extensively in industry, such as good electrical conductivity which superior to copper, better heat conductivity, lower density and higher plasticity [1,2,3]. The wide applications of aluminium and its alloys in industry are limited for the coarse grain size which degrades the mechanical properties [5,6,7]. Grain refinement is a favorite technique to improve simultaneously the plasticity and strength of metallic materials. That grain refining of aluminum is a key technique in aluminum processing. There have been a number of techniques for aluminum grain refining. Grain refining techniques can be classified into four categories as follows: the addition of grain refiner, grain refining by stirring and vibration during solidification, rapid solidification and severe plastic deformation [8]

Objectives

Results

Conclusion