Metallurgical patterns of the formation of W-Zr surface alloys via pulsed electron-beam processing

In this study, W-Zr surface alloys (SAs) were synthesized by low-energy high-current electron beam (LEHCEB) processing of preliminary deposited tungsten films on zirconium substrates in a single vacuum cycle. Then, their microstructure, as well as both chemical and phase compositions were investigated. Also, computer simulation of the dynamics of temperature fields was carried out. After LEHCEB processing of the Zr substrate with the pre-liminary deposited W film, the constituent element distributions were non-uniform over the surface of the W-Zr SA at the energy density of 3.5 J/cm2. Rising the energy density up to 5.5 J/cm2 resulted in a smoother and more homogeneous W-Zr SA. At the energy density of 3.5 J/cm2, the average tungsten content over the surface was 53 +/- 39 at.%, while it was only 26 +/- 2 at.% at 5.5 J/cm2. All W-Zr SAs consisted of the W phase (in different proportions), tungsten-rich solid solutions in the stabilized beta-Zr phase, and the W2Zr intermetallic compound. The contents of the beta-Zr and W2Zr phases enhanced with rising the energy density due to a greater amount of dissolved tungsten. Based on the obtained results, a scheme was proposed describing the formation of the SAs upon LEHCEB processing.