Analysis of Different Solution Treatments in the Transformation of β-AlFeSi Particles into α-(FeMn)Si and Their Influence on Different Ageing Treatments in Al–Mg–Si Alloys

Abstract

In the as-cast state, Al–Mg–Si alloys are not suitable for hot forming. They present low ductility due to the presence of intermetallic β-AlFeSi particles that form in the interdendritic regions during the solidification process. Homogenization treatments promote the transformation of these particles into α-(FeMn)Si particles, which are smaller in size and more rounded in shape, thus improving the ductility of the material. This paper analyses the influence of various solution treatments on the transformation of β-AlFeSi particles into α-(FeMn)Si particles in an Al 6063 alloy. Their effect on different ageing treatments in the 150–180 °C temperature range is also studied. An increase in the solution temperature favours greater transformation of the β-AlFeSi particles into α-(FeMn)Si, dissolving a greater amount of Si, thereby having a significant effect on subsequent ageing. We found that as the dwell time at a temperature of 600 °C increases, the rate of dissolution of the Fe atoms from α-(FeMn)Si particles exceeds the rate of incorporation of Mn atoms into said particles. This seems to produce a delay in reaching the peak hardness values in ageing treatments, which warrants further research to model this behaviour. The optimal solution treatment takes place at around 600 °C and the highest obtained peak hardness value is 104 HV after a 2 h solution treatment at said temperature and ageing at 160 °C for 12 h.

Influence of Aging on Corrosion Behaviour of the 6061 Cast Aluminium Alloy

“…Figure 5 d shows AlFeSi phase and microsize Mg 2 Si phase volume fraction changes at different artificial aged times (1–5 h) at 180 °C through image Pro Plus statistics and analysis. It was found that the proportion of AlFeSi phase and microsize Mg 2 Si phase in the matrix increased gradually from 1 h to 5 h. Nevertheless, Alvarez-Antolin et al [ 29 ] pointed out that AlFeSi intermetallics can undergo phase transformation and change their morphology during homogenization, but they are insoluble during solution heat treatment and aged stage in Al–Mg–Si alloys. The reason for the AlFeSi phase increase with aged time needs to be further studied.…”

Production and Aging Heat Treatment of Ceramic Reinforced Al6061 Matrix MMCs by Vacuum Infiltration Method

“…900ºC'de uygulanan ergitme yapıda α-AlFeSi intermetaliklerinin ve 540ºC'de 2 saat uygulanan çözündürme + 130ºC'de 18 saat yaşlandırma ise β-AlFeSi intermetaliklerinin oluşmasında etken rol oynamıştır [15]. Oluşması muhtemel α-AlFeSi ve β-AlFeSi intermetalikleri, sertlikteki artışlar için açıklayıcı olarak nitelendirilebilir [16]. Ayrıca takviye içerik ve oranları, yapıda oluşması muhtemel faz ve içeriklerin boyut ve şiddetine de doğrudan etki ettiği Şekil 4'de görülmektedir.…”

Casting and Solidification of Light Alloys

“…The analysis of the effect of processing the Al-Mg-Si solution on the transformation of β-AlFeSi particles into α-(FeMn) Si and the aging of the Al 6063 alloy were presented in [5]. It was found that the maximum hardness of 104 HV was reached following a solution treatment at a temperature of 600 • C for 2 h and aging at a temperature of 160 • C for 12 h.…”