The Preparation Of New Type Amorphous Refiner And Its Influence On The Structure And Properties Of A356 Alloy

In this paper,A356.2 alloy was chose as the matrix,which aimed to create a new type of amorphous alloy refining modifier.The work chose Al-Gd based binary alloy as the modifying agent to prepare different atom ratios of Al-Gd alloy.The rapid solidification procedure followed with X-ray diffraction?XRD?analysis,differential scanning calorimetry?DSC?analysis and discussing the glass forming ability of each alloy were orderly finished.After vacuum heat treatment,the received samples were characterized through transmission electron microscopy?TEM?.Finally,the type,structure and size of alloys crystallized precipitates were compared with the Al-Gd cast alloy containing same content of modifier.The modification with two different states of alloy contributed to characterize the average grain size,eutectic silicon modification case and the tensile properties of the A356.2 alloy.Satisfactorily,the qualities of A356.2 alloy modified by Al-Gd amorphous alloy were better in comparison to that inoculated by conventional refining modifier.4 factors and 3 levels orthogonal heat treatment experiment was arranged accord to L₉?3⁴?orthogonal table,and then the effect of heat treatment parameters on the microstructure and properties of A356.2 alloy were studied.Research shows as this:?1?A356.2 alloy incorporated with 0.5wt.%Al₉₂Gd₈ amorphous alloy was melted at750?for 10min.As a result,the average grain size of A356.2 cast alloy reached 41.43?m and the fine fibrous eutectic silicon was evenly distributed in the grain boundary.Simultaneously,the alloy yield strength?107.3MPa?,the tensile strength?211.5MPa?and the elongation?7.4%?respectively increased 5.8%,1.8%and 5.0%compared with A356.2alloy modified with Al₉₂Gd₈ cast alloy and raised 3.4%,11.9%and 17.6%compared with that inoculated with conventional refining modifier,respectively.?2?With the addition of 0.5wt.%Al₉₂Gd₈ amorphous alloy,the average grain size and the eutectic silicon average area respectively reached 50.21?m and 8.91?m² after T6 heat treatment.The alloy yield strength?235.6MPa?,the tensile strength?306.6MPa?,and the elongation?9.6%?respectively increased 5.4%,7.4%and 28%in comparison to A356.2alloy inoculated with conventional refining modifier.In terms of the tensile strength and the elongation rate,the A356.2 alloy with heat treatment was enhanced by 3.8%and 12.9%compared with 0.65wt.%Al₉₂Gd₈/A356.2 alloy.Otherwise,the enhancement of yield strength is unobvious.