Growing 'metallic wood' to new heights

Penn Engineers' "metallic wood" gets its useful properties and name from a key structural feature of its natural counterpart: porosity. As a lattice of nanoscale nickel struts, metallic wood is full of cell-sized pores that radically decrease its density without sacrificing strength. They have now solved a major problem preventing metallic wood from being manufactured at meaningful sizes: eliminating "inverted cracks," a kind of defect that has plagued similar materials for decades.