The microstructure and properties of nanostructured Cr-Al alloying layer fabricated by high-current pulsed electron beam

In this paper, the feasibility of an innovative surface alloying technique was successfully demonstrated in which Cr-Al alloying layer was fabricated on an Al substrate by high current pulsed electron beam (HCPEB) to enhance the surface properties. The microstructures of the alloying layer were investigated by means of X-ray diffraction (XRD), scanning electron microscope (SEM) and transmission electron microscope (TEM). The microhardness and corrosion resistance were also examined. After surface alloying by HCPEB irradiation, a mixture of Al and Cr elements was formed, which generated a Cr-Al alloying layer on the surface of Al substrate. Meanwhile, abundant nanostructured intermetallic compounds, such as Al8Cr5, AlCr2 and Al13Cr2, together with ultrafine Cr particles and Al (Cr) solid solution, were also formed in the alloying layers. In addition, both the microhardness and corrosion resistance were dramatically improved due to the addition of Cr element and the modified layer microstructure.