Terminal ballistic effects for 3D-printed multi-layered material consisting of Ti-6Al-4V alloy, metal matrix composite and porous titanium

The influence of the composition and structure of a multilayer titanium-based material on its behaviour under impact testing conditions was studied. The material consisted of four consecutive layers of: (i) metal matrix composite (MMC) based on Ti64 alloy (wt. 6.1% Al-4% V) reinforced with 40 vol % dispersed TiC particles, (ii) Ti64 alloy, (iii) porous commercial purity titanium (about 60% pores), and (iv) the bottom layer of Ti64 alloy. MMC and Ti64 alloy layers were deposited on a layer of porous Ti using a coaxial electron beam 3D printing method with a commercial Ti64 wire, and a specially designed cored wire as the feedstock. The overall density of the layered material was less than 3 g/cm³. An impact test conducted with a 7.62 mm calibre armour-piercing cartridge (with a bullet kinetic energy of 3430 J) demonstrated high ballistic resistance when a hard bullet core penetrated the sample to a depth of approximately 20 mm, where it was stopped within the porous titanium layer and subsequently ejected from the sample. The features of the microstructure of this four-layer material in different locations and their role in ballistic resistance are considered and discussed.