Microstructure and Properties of Vacuum Cast Sc-Containing Be–Al Alloys

The cross-sectional microstructure and mechanical properties of vacuum suction cast beryllium–aluminum (Be–Al) alloy rods with different additions of scandium (Sc) were firstly investigated. The vacuum suction casting process was numerically simulated with the filling time of 0.1 s and solidification rate of 870 °C/s roughly obtained. The sub-rapid solidification process rendered no amorphous phases but three kinds of distinguished microstructures, of which the crystallization type and grain size of Be in the central part varied with increasing additions of Sc. The Al3Sc phase could only exist with a high content of Sc. Rapid solidification hindered macro-segregation and resulted in secondary phases with homogeneous compositions. The 1.0 wt% addition of Sc caused microscopic shrinkage porosities in the center of alloy rod by changing temperature gradient at the liquid/solid interface front and crystallization interval. Central areas with refined microstructure had the highest macro-hardness; stiffer Sc-containing particles further increased the mechanical performances of alloys.