Microstructural Changes in Magnesium Alloy Mg‒Zn‒REE after Irradiation with Nanosecond Laser Pulses

Abstract

The results of electron microscopy and energy-dispersive X-ray microanalysis studies of the structure and composition of the surface and near-surface layers of the Mg–Y–Zn–Nd–Yb–Zr alloy system with a long-period phase after irradiation by nanosecond laser pulses are reported. It is shown that in two-phase alloy, a nanocrystalline MgO layer with a thickness from 5 nm to several hundreds of nanometers is formed on the surface in the α-Mg matrix region. A recrystallized layer of columnar crystallites with a thickness of ~1 μm and a lateral size of 0.2–1 μm, with inclusions of cubic MgO, is formed under this layer. In the area of the intermetallic compound (Mg₁₂YZn–REE phase of the 18R type), a three-layer amorphous–crystalline trilayer is formed; it consists of a (15–20)-nm-thick amorphous surface layer, a (0.1–0.3)-μm-thick crystalline layer of columnar crystallites with lateral sizes of 0.1–0.5 μm under it, and a ~1-μm-thick amorphous intermetallic layer.