Thermal roughening restrained by bulk chemical order:: Cu-Pd(17%)(115) versus Cu(115) and Cu3Au(1112) surfaces

In contrast with dense surfaces, pure metal vicinal surfaces exhibit a roughening transition temperature well below their melting point. Although the surface structure of the single step Cu-Pd(17%)(I 15) and Cu(I 15) is similar, it is pointed out that the two surfaces have a very different behavior for thermal step disordering. If the roughening temperature of Cu(I 15) is found to be of 380 K, the alloy surface does not roughen up to the vicinity of the bulk chemical order-disorder transition (T-c = 778 K). This result point out the interest of ordered alloys to produce high temperature stable flat surfaces. (C) 2002 Elsevier Science B.V. All rights reserved.