Differential Thermal Analysis and Differential Scanning Calorimetry Studies of Aluminum 3003 Alloys with Zn and Cu Addit
- PDF / 864,519 Bytes
- 10 Pages / 593.972 x 792 pts Page_size
- 93 Downloads / 201 Views
N
THE use of Al-Mn alloys of AA 3003 type in automotive applications, as in a heat exchanger, is well known and is becoming increasingly important. This alloy family is a kind of alloys that cannot be strengthened by heat treatment. Alloy development can be possible by different modifications. Solid solution strengthening by addition of certain alloying elements is one effective way to further improve their strength and corrosion behavior. Earlier work[1,2] showed that the microstructure and the properties of the alloys were affected by additions of different amounts of zinc as alloying elements. It was found that additions of Zn contributed to a finer grain structure and hardness improvements, and especially at 2.5 wt pct Zn, these effects had a maximum. It has also been found that this Zn effect was influenced by additions of Cu. The presence of up to 1.0 wt pct Cu increased the precipitation of secondary phases.[2] Zn has a large solubility and can be dissolved in the solid state in Al to high concentrations, and thus, the strength can be improved by solution hardening. Another interesting aspect of Zn alloying is that it provides the possibility of achieving corrosion protection to selected parts of the heat exchangers. The Zn additions lower the corrosion potential, and can thus be used in parts that can act as sacrificial anodes while other parts are being protected. The Cu contributes to the solid solution strengthening of the material, but it can also be used to alter the corrosion properties in different ways.[3] MAJED JARADEH, Postdoctoral in Materials Processing, and TORBJO¨RN CARLBERG, Professor Material Engineering, are with the Department of Engineering, Physics and Mathematics, Mid Sweden University, 851 70, Sundsvall, Sweden. Contact e-mail: [email protected] Manuscript submitted October 17, 2006. Article published online July 26, 2007. 2138—VOLUME 38A, SEPTEMBER 2007
AA3003 alloys contain Mn, Fe, and Si as alloying elements, and during solidification, primary particles as Al6(Mn,Fe) and a-Al(Mn,Fe)Si form in the alloy mainly as interdendritic eutectic networks.[4–6] The DTA analysis of the base alloy has earlier been carried out to determine the temperatures at which these precipitations occur. According to Ba¨ckerud et al.,[5] the precipitation sequence and type of intermetallic phases occurring in a 3003 alloy are as follows: L ) Al; dendritic network at 655 C L ) Al; dendritic network þ Al6 ðFe; MnÞ at 653 C L ) Al; Al15 ðFe; MnÞ3 Si2 at 641 C to 634 C Liq þ Al6 ðFe; MnÞ ) Al þ Al15 ðFe; MnÞ3 Si2 The current investigation aims at giving a better understanding of earlier obtained results from directional solidification[1] and DC-simulator[2] experiments of the influence of different Zn and Cu additions to 3003 alloys. Better knowledge in general of the solidification behavior, phase precipitation, and resulting microstructures is also a goal. II.
EXPERIMENTAL
The chemical composition of the as-cast aluminum AA 3003 alloy prior to Zn and Cu additions is given in Table I. The investigated sample comp
Data Loading...
