Synthesis of open-cell metal foams by templated directed vapor deposition

Low-density, open-cell nickel base superalloy foams have been synthesized b y a high-rate, electron beam-directed vapor deposition process and their me chanical properties evaluated. The deposition process uses an open-cell pol ymer foam template upon which is deposited a metal alloy coating. The elect ron beam evaporated flux was entrained in a rarefied transonic gas jet and propagated along the flow stream lines through the polymer structure. After vapor deposition, the polymer template was removed by low-temperature ther mal decomposition. The resultant ultralightweight metal foams consisted of a three-dimensional open cell, reticulated structure possessing hollow tria ngular ligaments with relative densities of <3%. Their mechanical integrity was increased by either pressureless or transient liquid phase sintering. The mechanical properties of these ultralightweight metal foams were compar able to theoretical predictions for open-cell, reticulated foams.