Ballistic performance of functionally graded boron carbide reinforced Al – Zn – Mg – Cu alloy

Abstract

Functionally Graded Materials (FGM) with graded ceramic content offer significant protection against high-velocity ballistic impacts. The incorporation of ceramic reinforcements helps in increasing the hardness of individual layers, and the presence of a ceramic-rich top layer offers a better ballistic resistance with fewer layers. In the present study, Boron carbide reinforced Al–Zn–Mg–Cu matrix FGM is fabricated by hot pressure-assisted sintering. Three FGMs of five layers, each with power-law indices (N = 0.5,1 and 2.5), are fabricated. FGM N = 2.5 shows the highest hardness at the top ceramic-rich layer (70 vol% B4C) was 266.7 HV. The highest compressive strength of 597 ± 8.97 MPa was achieved in FGM N = 2.5, 35.99% and 44.90%, higher than the FGM N = 1 and FGMN = 0.5, respectively. The 70 vol% B4C aids in dissipating the kinetic energy of the projectile, and ballistic tests carried out at 700 m/s show that FGM N = 1 and N = 2.5 offer better ballistic resistance with a 36.27% and 26.89% improvement in the depth of penetration as compared to N = 0.5. Our results show that an adhesive and abrasive friction mechanism is responsible for slowing the projectile within the FGM. Analytical studies such as calculating the Ballistic Performance Index and stress wave analysis corroborate the experimental results. The fabricated FGM N = 1 and N = 2.5 offer significant protection against projectile 7.62 Χ 39 mm type III+ level threats for velocities up to 700 m/s and can be used as light-weight armours.

Keywords

• Functionally graded material
• Powder metallurgy
• Particle reinforced composite
• Ballistic performance
• Impedance
• Armor material