Plasticity enhancement in Ni-P amorphous alloy/Ni/Zr-based metallic glasses composites with a sandwich structure

Using electrodeposition and chemical plating, Ni film and Ni-P film were coated on the surface of Zr-based amorphous alloy of Zr_41.2Ti_13.8Cu_12.5Ni₁₀Be_22.5 (Vit.1). The compression behavior of the bare Vit.1 pillars and the Vit.1 pillars with the Ni-coating and Ni-P/Ni-coating was studied. The Ni-P/Ni/Vit.1 pillars with "amorphous-crystalline-amorphous" sandwiched structure formed a "hard-soft-hard" composite, and the Ni/Vit.1 pillars formed a "soft-hard" composite. The experimental results show that the surface coating increases the density of shear bands in the Vit.1 pillars, resulting in the improvement of the compression ductility. The Ni-P/Ni/Vit.1 pillars have the largest engineering plastic strain of 21.3±1.0% for the "uniform plastic deformation", about 11.2 times of 1.9% of the bare Vit.1 pillars. The Ni-P/Ni-coating limits the propagation of shear bands, which leads to the initiation and formation of multiple shear bands. The technique developed in this work provides a new route to enhance the compression ductility of amorphous alloy at room temperature.