Effects of Mg Content on Microstructure and Mechanical Properties of Al-14.5Si-4.5Cu Alloy

Abstract

This study elucidates how Mg content affects the microstructure and mechanical properties of Al-14.5Si-4.5Cu alloy by adding 0.45 and 0.90 wt pct Mg. Primary silicon, eutectic silicon, acicular b-Al 5 FeSi, Al 2 Cu, and Al 5 Cu 2 Mg 8 Si 6 phases were observed under the as-cast condition in low-Mg alloy. In high-Mg alloy, a large proportion of the acicular b-Al 5 FeSi phase was converted to Chinese script Al 8 Mg 3 FeSi 6 phase. Neither the acicular b-Al 5 FeSi phase nor the Chinese script Al 8 Mg 3 FeSi 6 phase dissolved in the Al matrix during solution heat treatment. Tensile testing indicates that T6-treated high-Mg alloy containing the Chinese script Al 8 Mg 3 FeSi 6 phase is better than the T6-treated low-Mg alloy that contains the acicular b-Al 5 FeSi phase. The morphologies of Chinese script Al 8 Mg 3 FeSi 6 and acicular b-Al 5 FeSi phases affect the tensile properties of Mg-containing Al-14.5Si-4.5Cu alloys. Additionally, high-Mg alloy contains a higher concentration of Mg solute atoms in the Al matrix than low-Mg alloy, and so the former contains more k¢ precipitates (Al 5 Cu 2 Mg 8 Si 6 ) after T6-tempering treatment. The large amount of k¢ that precipitates in T6-treated high-Mg alloy may also enhance its tensile strength. The ultimate tensile strength (UTS) and elongation of the high-Mg alloy are superior to those of the low-Mg alloy.

Enhancement of the Mechanical Properties in Al–Si–Cu–Fe–Mg Alloys with Various Processing Parameters

“…From Figure 3d and the XRD analysis, it was presumed that the modification of the (β-Al 5 FeSi) phase did not occur even after the T6 heat treatment. Thus, the T6 heat treatment showed a negligible effect on the β-Al 5 FeSi phase, which was also observed by Costa et al [2] and Wu et al [23]. Oxygen discrete peaks were not observed, since the oxygen content was in a very narrow range, undetectable by X-ray analysis.…”

“…The recorded tensile strength values were 366, 388, and 420 MPa for alloy A, B, C, respectively, and the elongation rates were 10, 9.7, and 9.4 %. The obtained tensile strength of 420 MPa was greater than those previously reported by Wu et al [23] and Ke et al [8].…”

“…The increment in the Al 2 Cu phases with the increase of Si wt.% was interpreted as due to the increase by 20-fold of the diffusion coefficient of copper in aluminium, following the increase of silicon content in the alloy [7]. In Al-Si alloys, Mg can predominantly control and reduce the formation of Al 2 Cu phases [23], and this effect was compensated by increasing the silicon content, which increases the formation of the Al 2 Cu phases.…”

Two-Body Abrasive Wear Behaviour of In-Situ Al-TiC Particle Composites: Influence of TiC Reinforcement and Content in the Alloy Matrix and Experimental Parameters

“…3b, regions marked by A, arrow and B respectively). A detailed discussion about the Chinese script Fe-rich phase is available elsewhere [93,94]. The matrix structure of the composites remained practically unchanged due to TiC addition (Fig.…”

Effects of Cu/Mg ratio and heat treatment on microstructures and mechanical properties of Al–4.6Cu–Mg–0.5Ag alloys

“…The heat of U and q 0 precipitation of alloy AT8 still increases from 5.1 J/g to 6.3 J/ g. The next section on the electrical conductivity will interpret the result of the DSC in greater detail. The dissolution and precipitation of solute atoms influences the lattice structure of the alloy in the form of point defects that scatter the conduction electrons, resulting in variations in electrical conductivity [16,19]. Table 4 lists the electrical conductivities of four alloys under the hot rolling (C H ), as-quenched (after solution treatment and cold working, C 0 ), 24 h natural aging (C 01 ) and artificial aging (C AA ) conditions.…”