Microstructure, transformation characteristics and mechanical properties of thin TiNi films deposited from a planar magnetron source onto a cylindrical surface

Abstract
Thin TiNi films (17 - 5 microns thick) deposited from a planar magnetron source onto a 6.35 mm diameter centerless ground rod (average surface roughness is about 1 micron) and onto a polished one (average surface roughness is about 0.02 micron) have been characterized. The film deposited onto a ground rod breaks very easily and can be removed from the substrate only in small pieces. It was found that the external surface of the film replicates all the imperfection of the original ground surface. The film has a plate-like grain structure with the "plates" stacked across the grinding marks aligned along them and perpendicular to the film surface. These "plates" have very poor cohesion between each other, and film easily brakes apart along the grinding marks. The film deposited onto a polished rod is strong enough to be pulled from the surface cut into samples 25x1 mm, and mechanically tested. The grain structure, external surface, roughness, and mechanical properties of the film were found to be dependent on the incident angle while the transformation characteristics of the film are almost independent of it.