Local thermal property analysis by scanning thermal microscope of ultrafine-grained surface layer in copper and in titanium produced by surface mechanical attrition treatment

Ultrafine-grained surface layers were obtained by surface mechanical attrition treatment (SMAT) in copper and titanium samples. The thermal properties of the deformed layers were characterized using a scanning thermal microscope (SThM) that allows thermal conductivity to be mapped down to the submicrometer scale. A theoretical approach, based on this investigation, was used to calculate the heat flow from the probe tip to the sample and then estimate the thermal conductivities at different scanning positions. Experimental results and theoretical calculation demonstrate that scanning thermal microscope can be used as a powerful tool for the thermal property and microstructural characterization of ultrafine-grained microstructures.