Indentation damage characterisation in advanced materials

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The hardness of a material is one of the most fundamental mechanical properties that can be evaluated. Hardness significantly impacts properties relating to wear, and is therefore an extremely important parameter when developing materials for such applications. Surface treatments (e.g., shot peening, whereby the processed material is impacted with hard 'shot' beads) can also result in gradation of hardness, so depth profiles can provide extremely useful information about the efficacy of the process. With that in mind, the present NSERC RTI application is for an automated, state-of-the-art indentation system as an urgently needed replacement for an approximately 40-year old Vickers hardness tester that is no longer serviceable, and a similar age micro-Vickers that is also now proving unreliable. A replacement is urgently required in support of several major ongoing and recently awarded research programmes in the Faculties of Engineering and Science at Dalhousie.******We will be evaluating a broad variety of advanced materials with the requested system, including powder metallurgy (PM) and additive manufacturing (AM) processed light metals and ferrous alloys, high wear resistance cermets and coatings, conducting polymer composites, etc. We will also be assessing the effects of a novel ultrasonic pulsed water jet (UPWJ) method for ‘peening' PM and AM processed alloy surfaces; this 'green' technology, invented by a Canadian SME, offers the potential to revolutionise surface peening. The automated test system will allow hardness depth profiling, evaluation of indentation size effects (i.e. the dependence of hardness upon applied load), hardness mapping for multi-phase materials, and scratch testing. In addition, conversion of the diamond indenter tip to a flat diamond punch, will allow micropillar compression testing; here small square or cylindrical pillars can be milled on a surface using a focused ion beam (FIB) microscope, and then compression tested using the indentation unit.******The requested multi-functional indentation system also allows for a broad range of indentation loads, covering roughly five orders of magnitude up to maximum of 40 kg, giving significantly increased usability over our prior (and no longer functional) Vickers system. As noted above, hardness is one of the most fundamental materials properties, and consequently the applicability of this requested equipment is extremely broad. It is expected that it will support the work of faculty who are collectively supervising more than 30 HQP.**