The Preparation Technology Of Binary Particles Reinforced Aluminum Matrix Composites

Multi-walled Carbon nanotubes reinforced aluminum matrix composite with the volume fraction of 0.75%~5.56 % and ZL114A-Al hybrid composites reinforced with the ratio of MWCNTs to SiCp(silicon carbide particles) to be 5:1, 4:1, 3:1, 1:1, 1:3 respectively were fabricated by rotating friction extrusion processing(RFEP). The influence of the process parameters(rotational speed, n(rpm), feeding velocity, v(mm/s)), pin geometry and MWCNTs content on morphology and mechanical properties of MWCNTs/Al were analyzed. And the influence of the mixing ratio changes of MWCNTs and SiCp on the tensile strength of the composite was focused on.The results show that MWCNTs/ZL114 Al composites were fabricated successfully by rotary friction extrusion processing(RFEP). With the increase of the rotation speed(n), the tensile strength and elongation both increased at first and then decreased. the composite could get a good shape and homogeneous central area organization with the parameter of n=435rpm and v=0.6mm/s, the tensile strength and elongation of which were both superior to other parameters, it is thought that unsuitable heat input is the main reason resulting in the decrease of mechanical properties of the compositeThe more the pin stages were, the worse the composites formed. Under the action of the tool with one pin, the tensile strength and central hardness of the composites were both superior to that by the other two tools. Plasticized metal was in a downward and outward movement compelled by the pin with left-handed thread and a clockwise rotation. With the increase of pin progressions stages, the frequency of plasticized metal migrating from the center to the external also increased. So the tool with three pins could easily lead to holes defect.With the increase of MWCNTs content, surface crack was exacerbated and the tensile strength increased at first and then decreased. when the volume fraction of MWCNTs was 1.28vol%, the tensile strength increased by nearly 20% comparing with the substrate. The possible cause of the increase of was that internal stress tends to be uniform.When the ratio of MWCNTs and SiCp was 4 to1, the composite formed well and the tensile strength of which was 184 MPa, which compared with the substrate increased by nearly 7%. The orientation of MWCNTs might be the main reason for the increase of the tensile strength. And Excessive fragmentation of MWCNTs resulted in the drop of composite strength.