A new approach to evaluate irradiation hardening of ion-irradiated ferritic alloys by nano-indentation techniques

Abstract

a b s t r a c tThe present work investigates the irradiation hardening of Fe-based model ferritic alloys after Fe-ion irradiation experiments in order to deduce mechanistically based nominal hardness from the nanoindentation tests on the ion-irradiated surface. Ion-irradiation experiments were carried out at 290 • C with 6.4 MeV Fe 3+ ions. The constant stiffness measurement (CSM) was used to obtain the depthprofile of hardness. The results has been analyzed and discussed based on the Nix-Gao model and an extended film/substrate system hardness model. The depth-sensing nano-indentation techniques with CSM revealed that the hardness gradient of the unirradiated Fe-based model alloy can be explained through the indentation size effect (ISE). On the other hand, the gradient of ion-irradiated surface of these samples includes not only the ISE but also softer substrate effect (SSE). We propose a new approach to evaluate a nominal hardness, which may connect to the bulk hardness, from experimentally obtained nano-hardness depth profile data.

Nanostructure Variations and Their Effects on Mechanical Strength of Ni-17Mo-7Cr Alloy under Xenon Ion Irradiation

“…In order to gain the hardness of any certain dpa, Kasada et al 20) reported a new method to evaluate irradiation hardening for ion-irradiated materials. The average nanoindentation hardness data is plotted as H 2 versus 1/h, as shown in Fig.…”

Understanding the effects of ion irradiation using nanoindentation techniques

“…In contrast, there are few methods available for the characterisation of mechanical properties from such small volumes of material, and analyses regarding best practise and validity of using these techniques for irradiated materials are scarce. There have been several investigations which have used nanoindentation as a means to measure the effects of ion irradiation on mechanical properties [1][2][3][4][5][6][7][8][9][10][11][12]. The majority of investigations have been conducted using a Berkovich tip geometry and include various methods such as load-unload [1,2] and continuous stiffness measurement (CSM) [8][9][10][11].…”

Evaluation of Irradiation Hardening of P92 Steel under Ar Ion Irradiation

“…The difference in magnitudes of irradiation-induced hardening at different temperatures were shown in Figure 3, ∆H = H irr − H uni , where ∆H is defined as variable quantity of hardness after Ar ion irradiation, H irr is the hardness after Ar ions irradiation and H uni is the corresponding original hardness at the same depth. Commonly, the hardness data near the surface is not adapted to investigate the irradiation-induced hardening due to testing artifacts [26]. Besides, there are some challenges for the measurement of mechanical properties of ion implanted layers, including indentation size effect, pile-up effect, sink-in effect, and residual stresses.…”

“…In recent years, many studies on the irradiation hardening behavior of F/M steel have been done through tensile, Vickers hardness, or nanoindentation tests [26,[31][32][33][34]. Significant hardening was observed in HCM12A and T91 steels after irradiation with 2.0 MeV protons at 400 °C, while both steels irradiated at 500 °C showed a slight increase in their hardness [31].…”