Optical microscopy and microhardness tests on a secondary aluminium alloy
by M. Britchi, M. Olteanu, I. Pencea
International Journal of Materials and Product Technology (IJMPT), Vol. 14, No. 1, 1999

Abstract: A study of optical microscopy and microhardness was performed on an aluminium alloy manufactured from scrap which was either slowly cooled or ultrarapidly quenched by a melt-spinning method. The alloy composition (in weight %) is: 9.52 Si, 3.80 Cu, 2.85 Zn, 2.00 Fe, 0.50 Mn, 0.30 Mg, 0.30 Sn, 0.30 Ni, 0.20 Pb, 0.10 Ti, the balance being Al. The presence in the equilibrium composition of the cast alloy of some fragilizing compounds (especially of silicon and iron) formed at these high values, much higher than solubility limits, has been evidenced by optical microscopy. Ultrarapid quenching is one of the methods used for aluminium scrap recovery. A study on a sample cast in a wedge-shaped mould was made before the ultrarapid quenching of the present alloy. The variation of the alloy structure with solidification rate is presented as optical micrographs taken starting from the broad end (16 cm) and going down to the tapered (<4 mm) end of the wedge-sample. Microhardness values along the sample are also given, and the conclusion is that microhardness rises with the increase of the solidification rate of the alloy. The alloy was quenched ultrarapidly by a melt-spinning method when tapes of different thicknesses were obtained. Due to this treatment, the alloy hardness is increased by two processes: (i) structure finishing, and (ii) an extension of solubility registered in the case of the elements considered as impurities, especially Si and Fe. The tapes manufactured from the ultrarapidly quenched alloy were then compacted by cold pressing followed by hot extrusion, when a finite product was obtained as rods of ø = 3 and respectively, ø = 4 mm diameters. The products thus obtained were studied by optical microscopy and microhardness measurements.

Online publication date: Mon, 01-Nov-2010

The full text of this article is only available to individual subscribers or to users at subscribing institutions.

 
Existing subscribers:
Go to Inderscience Online Journals to access the Full Text of this article.

Pay per view:
If you are not a subscriber and you just want to read the full contents of this article, buy online access here.

Complimentary Subscribers, Editors or Members of the Editorial Board of the International Journal of Materials and Product Technology (IJMPT):
Login with your Inderscience username and password:

Username:        Password:          Forgotten your password?

Want to subscribe?
A subscription gives you complete access to all articles in the current issue, as well as to all articles in the previous three years (where applicable). See our Orders page to subscribe.

If you still need assistance, please email subs@inderscience.com