steel substrates). Moreover, low elastic modulus is more appropriate for preventing crack formation (if not for inhibiting crack growth). Musil [] proposed a design based on the concept of ceramic nanoparticles embedded in an amorphous metallic matrix. This can be produced either by co-sputtering of the elements in an argon/nitrogen gas atmosphere or by post-deposition nanocrystallization of an amorphous coating. However, correct selection of coating elemental composition and of the deposition parameters (e.g. substrate temperature and energy of vapour flux bombardment) is very important []. design is a deviation from the ceramic/ceramic nanocomposite coating proposed Musil’s by Veprek. The consideration of an amorphous metallic intergranular phase will reduce the effective elastic modulus of this type of coating, thereby making it more compliant and tough. However, the coating-substrate interface is still susceptible to corrosive attack through any defect in its ceramic phase. Leyland and Matthews proposed using the following for the design of wear-resistant nanostructured or glassy metallic coatings []: 1. Alloys of low-miscibility elements, because they have the potential for producing nanostructured and amorphous coatings. 2. Binary alloys of metal elements (doped to ‘nitride-forming’ transition supersaturation in B, C, or N) with another low-modulus, low-miscibility transition element. 3. Ternary, quaternary or higher mixtures of elements with widely differing atomic radii (including combinations not possible to achieve in or ‘conventional’, cast rapidly-solidified bulk metallic glass systems).
steel substrates). Moreover, low elastic modulus is more appropriate for preventing crack formation (if not for inhibiting crack growth). Musil [] proposed a design based on the concept of ceramic nanoparticles embedded in an amorphous metallic matrix. This can be produced either by co-sputtering of the elements in an argon/nitrogen gas atmosphere or by post-deposition nanocrystallization of an amorphous coating. However, correct selection of coating elemental composition and of the deposition parameters (e.g. substrate temperature and energy of vapour flux bombardment) is very important []. Musil’s design is a deviation from the ceramic/ceramic nanocomposite coating proposed by Veprek. The consideration of an amorphous metallic intergranular phase will reduce the effective elastic modulus of this type of coating, thereby making it more compliant and tough. However, the coating-substrate interface is still susceptible to corrosive attack through any defect in its ceramic phase. Leyland and Matthews proposed using the following for the design of wear-resistant nanostructured or glassy metallic coatings []: 1. Alloys of low-miscibility elements, because they have the potential for producing nanostructured and amorphous coatings. 2. Binary alloys of ‘nitride-forming’ transition metal elements (doped to supersaturation in B, C, or N) with another low-modulus, low-miscibility transition element. 3. Ternary, quaternary or higher mixtures of elements with widely differing atomic radii (including combinations not possible to achieve in ‘conventional’, cast or rapidly-solidified bulk metallic glass systems).
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