Process for the production of Al-Fe-V-Si alloys

Abstract

The present invention relates to an improved process for the production of high strength and high wear resistant Al-Fe-V-Si alloys. The present invention comprises modifying / blocking primary intermetallic phases as well as interdendritic silicide phases by treating the melt with elemental magnesium or magnesium bearing master alloys to get a structure containing uniform distribution of intermetallic phases. The uniform distribution of primary and interdendritic phases are obtained with addition of magnesium or magnesium bearing master alloys because morphology of the interface changes resulting in the creation of more nuclei. It also breaks dendrite of the primary particles leading to structural change and fine particles. The present invention is useful for the industries engaged in production of high strength wear resistant aluminium alloys which are widely used in aerospace, transport and other engineering sectors.

Description

[0001] The present invention relates to an improved process for the production of high strength and high wear resistant Al--Fe--V--Si alloys. The present invention will be useful for the industries engaged in production of high strength wear resistant aluminium alloys which are widely used in aerospace, transport and other engineering sectors.[0002] In the general melting and casting process, the wide differences of densities and melting point of Al, Fe, V and Si couple with low diffusivity of Fe, V in Al pose problems in producing cast homogeneous structure. Al--Fe--V--Si alloys are generally produced and shaped through a costly technique or rapid solidification--powder compacting--extrusion / rolling route. In the prior art rapid solidification processes, such as atomization and melt spinning are used to obtain rapidly solidified alloy powders or ribbons respectively.[0003] U.S. Pat. No. 2,963,780 discloses a method for obtaining improved tensile strength at 350.degree. C. in alumin...

AI Technical Summary

Benefits of technology

[0010] The main object of the present invention is to establish melting treatment process for the production of cast and mechanically worked high strength and high wear resistant Al-fe-V--Si alloys leading to superior properties.

[0025] The process of present invention makes use of melting and alloying in a furnace. Casting are made in die casting or in permanent mould for ensuring a cooling rate 10-50.degree. C. / s, which is common in foundry practices. The microstructure of the cast materials reveals ten-armed star shaped particles with composition similar to Al.sub.3F.sub.3 with some amount of V and Si along with other interdendritic Al--Fe-silicide phases. These star shaped particles act as notches, which are deleterious to the toughness of the materials. Moreover, the chunky star shaped particles prevent proper feeding of the casting which results in microporosity in castings. Thus, the mechanical properties of the samples deteriorate to a greater extent.

Problems solved by technology

In the general melting and casting process, the wide differences of densities and melting point of Al, Fe, V and Si couple with low diffusivity of Fe, V in Al pose problems in producing cast homogeneous structure.

However, alloys obtained herein have low engineering ductility at room temperature and thus cannot be used in structural applications where a minimum tensile elongation of about 3% is required, for example in gas turbines.

Rapid solidification techniques are however, capital intensive and require high skill of operation because:

(i) the cooling rate is very high (10 to 10) which is difficult to achieve unless huge capital cost equipment is used

(ii) the powders / ribbons so obtained are not of uniform size leading to deterioration of mechanical properties

(iii) the steps of consolidation of the rapidly solidified alloy powders / melt spin ribbons and process to shape give additional cost to the technique

(iv) the product capacity is limited to a small size only because the ribbon or powder so obtained are compacted or sintered to a small for obtaining homogeneous structure.