Formation of novel flower-like silicon phases and evaluation of mechanical properties of hypereutectic melt-spun Al-20Si-5Fe alloys with addition of V

In this work, rapidly solidified hypereutectic Al-20Si-5Fe-. XV (X=0, 0.5 and 1) alloys were fabricated by melt spinning under vacuum. Microstructural and spectroscopic analyses were performed using SEM, TEM, TEM-MAPing, TEM-EDS and XRD measurements. Mechanical properties of the alloys were determined using DSI measurements. Experimental results indicated that addition of 0.5. wt% V to melt-spun Al-20Si-5Fe alloys induced formation of a novel flower-like Si phase. And addition of higher amount V (1. wt%), caused formation of refined Si phases and mostly hindered formation of Fe-bearing intermetallics. Observations along with manuscript strongly indicate that V modifies the Si phases by the impurity induced twinning (IIT). Changes in the dynamic microhardness of the samples were mainly determined by the size of Si phases. Addition of vanadium led to quite lower elastic modulus in the vanadium added alloys compared to base alloy. © 2014 Elsevier B.V.Firat University Scientific Research Projects Management Unit 110M517 National Council for Scientific Research British Association for Psychopharmacology: 2010/111The authors would like to thank the Scientific and Technological Research Council of Turkey (TÜBİTAK) for funding the Project (Project number 110M517 ). The authors would like to thank the Gaziosmanpaşa University Department of Scientific Research Projects (BAP) for funding the project (Project number 2010/111 ). The authors wish to record their grateful thanks to Prof. Soon-Jik Hong from Kongju National University (KNU) for TEM and SEM works

Structural and mechanical properties of hypereutectic AlSiFe powders and a new method for determination of sintering temperature

In this study, the effect of Si amount on the microstructure, crystal structure and some mechanical properties of Al-(20,25,30 wt%)Si–5Fe powder mixtures produced by high energy ball milling method was investigated by determining the sintering temperature. In the X-ray diffraction analysis, no inter-metallic phases were found except for the Al, Si and Fe phases of the powder mixtures. The X-ray diffraction patterns were analyzed by the Rietveld method to determine amounts of the Al, Si and Fe elements in the powder mixtures. From the scanning electron microscopy analysis, it is seen that as the amount of Si increases, there is a marked decrease in the grain size of powders. In the micro-indentation tests performed at room temperature, the hardness and elastic modulus values of the pelletized powders were found to increase with the amount of Si. It was also found that the Al-20Si-5Fe powder mixture with the lowest Si content had the highest damping capability. The high temperature micro-indentation tests showed that the resulting Al-(20,25,30 wt%) Si-5 Fe powder mixtures started to consolidation at 200 °C and completed the consolidation at 400 °C. This method can be used as an alternative method in the determination of the sintering temperature of materials. © 2017110M517This research was supported by TUBITAK (Project No.: 110M517 )

Formation of the Fe-Containing Intermetallic Compounds during Solidification of Al-5Mg-2Si-0.7Mn-1.1Fe Alloy

© The Author(s) 2018. Iron (Fe) is the most common and the most detrimental impurity element in Al alloys due to the formation of Fe-containing intermetallic compounds (IMCs), which are harmful to mechanical performance of the Al-alloy components. In this paper we investigate the formation of Fe-containing IMCs during solidification of an Al-5Mg-2Si-0.7Mn-1.1Fe alloy under varied solidification conditions. We found that the primary Fe-containing intermetallic compound (P-IMC) in the alloy is the BCC α-Al15(Fe,Mn)3Si2 phase and has a polyhedral morphology with {1 1 0} surface termination. The formation of the P-IMCs can be easily suppressed by increasing the melt superheat and/or cooling rate, suggesting that the nucleation of the α-Al15(Fe,Mn)3Si2 phase is difficult. In addition, we found that the IMCs with a Chinese script morphology is initiated on the {1 0 0} surfaces of the P-IMCs during the binary eutectic reaction with the α-Al phase. Both the binary and ternary eutectic IMCs are also identified as the BCC α-Al15(Fe,Mn)3Si2 phase. Furthermore, we found that the Fe content increases and the Mn content decreases in the Fe-containing intermetallic compounds with the decrease of the formation temperature, although the sum of the Fe and Mn contents in all of the IMCs is constant.EPSRC Grant EP/H026177/1