Crystallographic orientation-spray formed hypereutectic aluminium-silicon alloys

Abstract

Aluminium-silicon alloys have been wide accepted in the automotive, electric and aerospace industries. Preferred orientation is a very common condition for metals and alloys. Particularly, aluminium induces texture during the forming process. The preparation of an aggregate with completely random crystal orientation is a difficult task. The present work was undertaken to analyse the texture by X-ray diffraction techniques, of three spray formed hypereutectic Al-Si alloys. Samples were taken from a billet of an experimental alloy (alloy 1) and were subsequently hot-rolled and cold-rolled (height reduction), 72% and 70%, respectively. The other used samples, alloys 2 and 3, were taken from cylinders liners. The results from the Laue camera showed texture just in the axial direction of alloy 3. The pole figures also indicated the presence of a typical low intensity deformation texture, especially for alloy 3. The spray formed microstructure, which is very fine, hinders the Al-Si texture formation during mechanical work.

An Al–Si–Ti hierarchical metal–metal composite manufactured by co-spray forming

“…In the 1 mm thick strip and consistent with the EBSD data, there was again no strong texture in ␣-Al, Si or Ti. Although conventional Al alloys often develop a strong 1 1 1 or other ␣-Al texture during extrusion, texture development in spray formed and extruded hypereutectic Al-Si alloys studied in detail by X-ray pole figure analysis has previously been shown to be weak, even after an extrusion reduction of ∼70% (Santos et al, 2005) We propose that particle stimulated nucleation (PSN) of dynamic recrystallization in Al-12Si due to the high number of ∼1 m hard Si particles may have relieved accumulated strain energy and undermined the development of a pronounced sub-grain structure and macro-texture (Humphreys, 1977). The ␣-Al grain size in this study was largely insensitive to the extent of deformation suggesting that PSN of recrystallization in the dilute ␣-Al (limited/no solute drag) by the Si was comparatively easy at all stages of processing.…”