Effect of Cd on Mechanical Properties of Al-Si-Cu-Mg Alloys under Different Multi-Stage Solution Heat Treatment

Abstract

Multi-stage heat treatment is an important method to improve the mechanical properties of Al-Si-Cu-Mg aluminum alloys. In this paper, the multi-stage heat treatment was carried out for the Cd-free and Cd-containing alloys. The experimental results show that the addition of Cd promoted the precipitation of Q″ and θ″, which led to the formation of a large number of fine, dispersed precipitates and a higher yield strength (YS) and ultimate tensile strength (UTS) for the Cd-containing alloys. The addition of Cd also altered the optimal heat treatment parameters. For the Cd-free alloys, the Cu-rich phase fully dissolved after three-stage heat treatment, and the YS and UTS of the three-stage heat-treated alloys were higher than their two-stage heat-treated counterparts. For the Cd-containing alloys, the three-stage heat treatment led to the precipitation of Cd-rich low melting point phases, caused defects, and reduced the mechanical properties of the alloy. The size and volume fractions of the precipitates were significantly less than those of the alloys after two-stage heat treatment and the strength of the alloys decreased. Therefore, the solution time should be strictly controlled for Cd-containing Al-Si-Cu-Mg alloys.

THERMOPHYSICAL PROPERTIES OF HYPOEUTECTIC, EUTECTIC AND HYPEREUTECTIC Al-Si AUTOMOTIVE ALLOYS UNDER AGEING TREATMENT

“…Double aging peaks with comparable profiles are observed for all when the alloys are subjected to aging treatments at different temperatures for one hour. Similar observations have also been reported by several investigators [14,22,23]. The precipitation behaviour of such alloys consists of the following sequence.…”

“…At the start of aging, fine and profuse GP zones distribute evenly in the matrix, and then their influence on strengthening is significant. Then again at the midway stage of aging metastable phases are created and kept semi-coherence with the matrix which resists the dislocation movement efficiently, thus having some strengthening effect [22]. At the transition stage from GP zones to metastable phases, these GP zones are significantly dissolved so the number of GP zones is significantly reduced.…”

From Bauxite as a Critical Material to the Required Properties of Cast Aluminum Alloys for Use in Electro Automotive Parts

“…Major Si [18] Cu [19] Mg [20] Mn Insignificant Insignificant [21] Zn [22] Minor Fe [23] Pb Insignificant Insignificant Insignificant [24] Sn [25] In [26] Be [27] Cr [28] Ni [29] Zr [30] Mo [31] Sc [32] La [33] A literature review has shown that there are commercial HPDC alloys (e.g., AlSi7Mg, AlSi10MgMn) available on the market which can be utilized to create electro automotive parts with those essential characteristics. The mechanical properties of these alloys can be [25] In (age hardening); dispersion strengthening; solid solution hardening; grain refinem teration of metallic and intermetallic phases; grain growth suppression at high tem tures; and so on. The mechanical properties of cast aluminum alloy components termined largely by the shape, size and distribution of precipitated particles in the num matrix.…”

“…More information regarding the impact of each alloying element on the mechanical properties of cast aluminum alloys can be found in the corresponding references listed in Table 3. Sn [25] In [26] Be [27] Cr [28] Ni [29] Zr [30] Mo [31] Sc [32] La [33] A literature review has shown that there are commercial HPDC alloys (e.g., AlSi7Mg, AlSi10MgMn) available on the market which can be utilized to create electro automotive parts with those essential characteristics. The mechanical properties of these alloys can be [33] A literature review has shown that there are commercial HPDC alloys (e.g., AlSi7Mg, AlSi10MgMn) available on the market which can be utilized to create electro automotive parts with those essential characteristics.…”

Microstructure and Mechanical Properties of Cast Al-Si-Cu-Mg-Ni-Cr Alloys: Effects of Time and Temperature on Two-Stage Solution Treatment and Ageing

“…Moreover, the needle-like Al 5 FeSi brittle phase formed in the alloy tends to cause stress concentration and reduce the mechanical properties of the Al-Si alloy. Consequently, this remains a challenge for Al-Si alloys [ 4 , 5 , 6 , 7 , 8 ].…”