Modification of Al-10Si-2Cu alloy surface by intensive pulsed electron beam

The study reports on the electron-beam processing (energy of accelerated electrons 17 keV, electron beam energy density ES = 10, 20, 30, 40, and 50 J/cm2, pulse duration 50 and 200 μs) of Al-10wt%Si-2wt%Cu alloy (silumin) surface. The important outcome to emerge from the study is a correlation between surface microhardness and electron beam energy density. As revealed, a maximal microhardness value is at ES = (30–40) J/cm2, being more than 1.6 times higher than the characteristic of the untreated material. The research has pointed out the electron-beam processing of silumin at ES = 10 J/cm2 causes the intensive destruction and microcracking along grain boundaries with particles of intermetallic compounds, as well as the globularization of cementite lamellae in eutectics. The irradiation of silumin by an electron beam (ES = 30–50 J/cm2) is shown to bring about the origination of micropores in the surface of samples, the dissolution of silicon, the globularization of intermetallic inclusions; in addition, a sub-micro-sized crystal structure of high-speed cellular crystallization forms. Finally, the electron-beam processing of silumin leads to the saturation of Al-based crystal lattice with alloying and impurity elements.