A New Alloy for Nextgen Lightweight Armor

Song Cai
Fort Wayne Metals Research Products Corp., Indiana, United States

Keywords: super-elastic, shape memory, large energy absorption

Our recent study shows that a NiTiNb alloy is capable of absorbing large amount of energy without permanent deformation. After properly cold formed and heat treated, it shows super-elasticity with an upper-plateau stress ~1400 MPa and an elastic strain of ~6% when tested at a very low strain rate, indicating that parts made out of this alloy can absorb ~80 MJ per cubic meter deformation energy and still able to return its original shape without obvious damage. The tensile fracture strength is close to 2000 MPa, and elongation is ~16%. The estimated fracture energy (based on the tensile stress strain curve) is ~250 MJ per cubic meter. It also shows a high resistance to localized deformation or necking, which may increase the resistance to the fragmentation protection as well. These numbers suggest that NiTiNb alloys could replace steels and or binary NiTi alloys as new material for the Next gen Lightweight Armor.