High-Temperature Scanning Indentation: A new method to investigate in situ metallurgical evolution along temperature ramps

Abstract

A new technique, High-Temperature Scanning Indentation (HTSI), is proposed to investigate metallurgical evolution occurring during anisothermal heat treatments. This technique is based on the use of high-speed nanohardness measurements carried out during linear thermal ramping of the system with appropriate settings. A specific high-speed loading procedure, based on a quarter sinus loading function, a creep segment and a three-steps unloading method, permits the measurement of elastic, plastic and creep properties. The indentation cycle lasts one second to minimize thermal drift issues. This approach enables quasi-continuous measurements of elastic modulus and hardness as a function of temperature in much shorter times than previous techniques. The HTSI technique is validated on fused silica and pure aluminum. The application to cold-rolled aluminum undergoing thermal cycling highlights the potential of the HTSI technique to investigate in situ thermally activated mechanisms linked with microstructural changes such as viscoplasticity, static recovery and recrystallization mechanisms in metals. Results on aluminum were confirmed using Electron Back-Scattering Diffraction measurements.

Current trends in nanomechanical testing research

“…A significant trend pervading this focus issue is the strongly increasing use of nanoindentation as a high-throughput method for producing large amounts of data [26][27][28][29][30][31], which are then analyzed with emerging data science algorithms. The former is made possible through recent technical developments by hardware manufacturers which aim at performing a single indentation within no more than 1 s (KLA: Express Test and NanoBlitz, Bruker: XPM, Alemnis: UHSR, and others).…”

“…Owing to intense research and development activities during the past decade, nanoindentation has been successfully expanded to applications at high temperatures. This has proven highly beneficial for investigating not only the deformation behavior of high-temperature materials [37,38], but also the fundamental effects of heat treatments [31]. In addition, the focus issue features a study conducted at cryogenic temperatures [39], which underscores that progress is also being made in this direction.…”

Micro-Indentation of oxidized low carbon steel to evaluate properties of oxides

“…Several models have been developed to evaluate adhesion of thin film on a substrate [10][11][12][13][14][15][16]. Recently, indentation tests at high temperature have been successfully carried out, overcoming technical difficulties (thermal drift, degradation of diamond indenter…) [17][18][19][20]. In the present paper, Room Temperature (RT) indentation of pre-oxidized samples is carried out as a first step, to demonstrate the capability of the approach which combines:…”