Investigation of the Effect of Sub-rapid Solidification Processes on the Microstructure and Mechanical Properties of Al86Cu6Co2Y6 (at.%) Alloy

The effect of cooling rate on the microstructure and mechanical properties of the Al86Cu6Co2Y6 (at.%) alloy is studied in copper mold casting and melt spinning processes. The micro-hardness values of the copper-mold rods (248.4 +/- 10.7 HV) are more than 3 times that of the conventional casting. Moreover, yield strength at room temperature has increased significantly by 67% (301 +/- 13 MPa). The plastic strain increased from 4 to 7% during copper mold casting due to the microstructure refinement, extended solid solubility of elements, homogeneously distributed of the fine eutectic and intermetallic phases (Al3Y, AlCu, AlCu3, Al3Y5) along with the matrix. However, a further increase in the cooling rate up to about 6.9 x 10(6) Ks(-1) obtained by the Lin and Johnson method during melt spinning can even inhibit the crystallization process. The amorphous ribbons exhibit a remarkable micro-hardness and tensile strength of 265.5 +/- 12.6 HV and 701 +/- 19 MPa, respectively. Non-crystalline structure with a lack of dislocations and grain boundaries results in such a high level of strength. [GRAPHICS]