A metallized aluminum nitride substrate (40) has a first layer (42) of deposited metal, comprising chromium, chromium oxide, and an aluminum nitride/chromium oxide complex represented by the formulaAl.sub.a N.sub.b O.sub.c Cr.sub.dwhere a, b, c and d are numbers representing relative combining ratios. The first layer is formed by sputtering about 10-500 .ANG.ngstroms of chromium onto the substrate under vacuum, and then heating the substrate in an oxygen-containing atmosphere at conditions of time and temperature sufficient to convert at least portions of the deposited chromium to chromium oxide, in order to form an adherent metal system. A second layer (44) of metal such as chromium covers the first layer. A third layer (46) of metal is deposited on the second layer in a manner sufficient to prevent oxidation of the second layer.