Analysis of the Microstructure and Mechanical Properties of a New Wrought Alloy Based on the ((Al) + Al4(Ca,La)) Eutectic

This paper examines manufacturability problems of a new Al-Ca-La-Mn alloy in the process of pressure treatment. Electron microscopy and X-ray diffraction analysis were used to perform a detailed study of the structure of the alloy in the cast state and after thermomechanical treatment under different conditions. The cast structure of the alloy is shown to consist of the Al-based solid solution (Al) and Al-4(Ca,La) eutectic phase, whose volume fraction is similar to 15%. The metallographic analysis of the alloys subjected to hot and cold rolling, as well as cold drawing, was performed; a substantial refining of eutectic intermetallics compared to that in the cast state was found. In particular, the homogeneous distribution of submicron spherical particles (300-500 nm in size) in the volume of composite material is observed, which are efficient stabilizers of the structure upon recrystallization. The obtained samples of rolled sheets demonstrate the high thermal stability of the structure and properties during long-term isothermal holding at 250 and 350 degrees C. In particular, it has been shown that the 10-h annealing of cold-rolled sheet 1 mm thick at 250 degrees C leads to a decrease in the hardness only by similar to 15%. The most favorable conditions for manufacturing the rolled sheets allow us to reach high mechanical properties (an ultimate strength of 240-290 MPa, a yield strength of 200-250 MPa, and a relative elongation of 5.5-15.5%).