Precipitation and Age-Hardening in Al-Si-Cu-Mg-Fe Casting Alloys

Yao, Ji Yong; Edwards, Geoffrey A.; Graham, D.A.

doi:10.4028/www.scientific.net/msf.217-222.777

Cited by 23 publications

(10 citation statements)

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“…It reduces the time to reach the peak hardness [10]. For Al x Mg y Si z (Cu) alloys, at least four different types of precipitates have been reported [11,12]: Mg 2 Si (b), Al x Cu y Mg z Si w (Q), Al 2 CuMg and CuAl 2 (u).…”

Section: Introductionmentioning

confidence: 99%

The influence of copper content on intergranular corrosion of model AlMgSi(Cu) alloys

Zhan

Mol

Hannour

et al. 2008

Materials & Corrosion

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Application prospects in automotive and aerospace industry have led to extensive studies on AA6xxx alloys in recent years. Varying amounts of Mg, Si and Cu and heat treatments are used to achieve the desired mechanical properties in these alloys. In this investigation, a series of tests have been designed and carried out on model AlMgSi(Cu) alloys to investigate the effects of Cu, Mg and Si composition and heat treatments on the corrosion properties for a range of Cu content levels (0.03, 0.15 and 0.80 wt%, respectively).The results indicate that the localized corrosion susceptibility of the model alloys primarily increased with Cu content. The Si and Mg content and ratio do not appear to have a significant effect on the local corrosion behaviour. Heat treatment can improve the corrosion resistance. However, this effect is small compared to that of the Cu content for the range of model alloys investigated. Intergranular corrosion will occur by micro-galvanic coupling between the cathodic AlMgSi(Cu) (Q) phase precipitates and the aluminum matrix adjacent to the particles. The increasing susceptibility to intergranular corrosion with Cu content can be attributed to an increased formation of Q phase particles.

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Section: Introductionmentioning

confidence: 99%

The influence of copper content on intergranular corrosion of model AlMgSi(Cu) alloys

Zhan

Mol

Hannour

et al. 2008

Materials & Corrosion

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“…In recent years, the process of heat treatment for Al -Si base alloys containing Cu and/or Mg element has been investigated in certain aspects [1][2][3][4]. The age-hardening mechanisms responsible for strengthening is based on the formation of intermetallic compounds during decomposition of a metastable supersaturated solid solution obtained by solution treatment and quenching (precipitation hardening).…”

Section: Introductionmentioning

confidence: 99%

Age-hardening behavior of cast Al–Si base alloy

Zhao

et al. 2004

Materials Letters

213

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“…According to Yao et al, 56 the peak hardening of the Al-7.1%Si-3%Cu-0.39%Mg alloy is caused by the combined precipitation of plate-like 6' precipitates and needle-like precipitates. Some of these needles have the same crystal structure as the L and fi" phases where L phase has been reported as a precursor of the Q' phase.…”

Section: Al 2 Cu Equilibriummentioning

confidence: 99%

Effect of additives on the mechanical properties and machinability of a new aluminum-copper base alloy /

Elgallad¹

2010

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The present dissertation is aimed at investigating the effects of additives on the mechanical properties and machinability of the 220 alloy which is a new Al-2%Cu-1.3%Si-0.4%Mg casting alloy intended for automotive applications. The research involved here was accomplished through two types of study: (i) study of mechanical properties; (ii) and study of machinability. The study of mechanical properties was proposed to examine the effects of Sr, Ti, Zr, Fe, Mn, and Ag as well as of free-cutting elements, specifically Sn and Bi, on the mechanical properties of the 220 alloy in both the as-cast and heat-treated conditions. The mechanical properties in question include tensile, hardness, and impact properties which were all evaluated at room temperature. The study of machinability was devoted to examining the drilling and tapping performance of four 220 based-alloys as well as of A206 alloy which was selected for a comparative study on the machinability of this particular alloy and that of 220 alloy. The four 220 based-alloys were selected from amongst the alloys prepared in the first study and include: (i) 220 alloy; (ii) 220 alloy + Ti + Zr; (iii) 220 alloy + Ti + Zr + Sn; and (iv) 220 alloy + Ti + Zr + Bi. The machining performance was evaluated based on the calculation of the cutting force, cutting moment, and tool life, as well as on the investigation of chip characteristics. Tool life was expressed as the number of holes drilled/tapped up to the point of tool breakage.An assessment of the microstructure reveals that A^Cu, AlsMggSiôC^, and the Chinese script-like a-Ali5(Fe,Mn)3Si2 phases are the main microstructural constituents of the 220 alloy. The absence of free Si in the microstructure implies that the Si-content was consumed in the formation of the Al-Fe-Si and Al-Cu-Mg-Si intermetallic phases. The platelet-like /?-AlsFeSi phase was not in evidence because of the higher Mn:Fe ratio (~1) of the 220 alloy which promotes the formation of the a-Fe phase at the expense of the /?-Fe phase. The addition of Sr refines the morphology of the ct-Fe Chinese script phase to a certain extent, resulting in the even distribution of the particles of this phase within the aluminum matrix. The combined addition of Ti and Zr causes a reduction in the grain size by about 68% compared to the non-grain-refined base 220 alloy. This reduction may be ascribed to the formation of Zr-Ti particles which act as nucleation sites for small equiaxed grains of cc-Al. Tin precipitates in the form of /?-Sn particles which appear as small non-uniformly distributed clusters usually solidified within the AbCu phase network. Bismuth and /?-Sn particles were found undissolved in the Almatrix after heat treatment, thereby making it possible to induce their free-cutting action during machining.Results from the evaluation of the mechanical properties show that, because of the low Si content, the effects of Sr on the mechanical properties with respect to the modification of silicon eutectic do not come into play. The role of Sr in refining th...

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Precipitation and Age-Hardening in Al-Si-Cu-Mg-Fe Casting Alloys

Cited by 23 publications

References 0 publications

The influence of copper content on intergranular corrosion of model AlMgSi(Cu) alloys

The influence of copper content on intergranular corrosion of model AlMgSi(Cu) alloys

Age-hardening behavior of cast Al–Si base alloy

Effect of additives on the mechanical properties and machinability of a new aluminum-copper base alloy /

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