Titanium Alloy Lattice Structures with Millimeter Scale Cell Sizes

Titanium sandwich panels with cellular cores of a uniform 1-5 mm diameter open cell size are well suited for impact energy absorption and cross flow heat exchange applications. Periodic cellular structures (lattices) made from high specific strength, high temperature alloys are preferred for these multifunctional uses. A diffusion bonding method has been applied here to make cellular lattice structures from a Ti-6A1-4V alloy. To illustrate the approach, lattice structures with both square and diamond collinear topologies, a 2 mm open cell size, and a relative density of 15% were made from 254 mu m diameter titanium alloy wires. These structures were found to have a compressive strength of 40 +/- 5 MPa that was controlled by plastic yield followed by buckling of the struts. The cellular structures have been brazed to titanium alloy face sheets to create sandwich panel structures that appear well suited for multifunctional applications up to 420 degrees C.