2 resultados para RARE EARTH ALLOYS
em Universidad Politécnica de Madrid
Resumo:
An inverse optimization strategy based on crystal plasticity finite element simulations of polycrystals was used to obtain the critical resolved shear stresses of two Mg?1%Mn alloys containing neodymium from macroscopic experimental data. It was found that, with respect to pure Mg, the presence of Nd increases the CRSSbasal, CRSStwinning, and the CRSSbasal/CRSStwinning ratio and decreases the CRSSnon-basal/CRSStwinning ratio. Additions of neodymium as high as 1 wt% result in similar CRSSs values for all deformation modes and, thus, in an isotropic yielding behavior.
Resumo:
One of the main limiting factors in the development of new magnesium (Mg) alloys with enhanced mechanical behavior is the need to use vast experimental campaigns for microstructure and property screening. For example, the influence of new alloying additions on the critical resolved shear stresses (CRSSs) is currently evaluated by a combination of macroscopic single-crystal experiments and crystal plasticity finite-element simulations (CPFEM). This time-consuming process could be considerably simplified by the introduction of high-throughput techniques for efficient property testing. The aim of this paper is to propose a new and fast, methodology for the estimation of the CRSSs of hexagonal close-packed metals which, moreover, requires small amounts of material. The proposed method, which combines instrumented nanoindentation and CPFEM modeling, determines CRSS values by comparison of the variation of hardness (H) for different grain orientations with the outcome of CPFEM. This novel approach has been validated in a rolled and annealed pure Mg sheet, whose H variation with grain orientation has been successfully predicted using a set of CRSSs taken from recent crystal plasticity simulations of single-crystal experiments. Moreover, the proposed methodology has been utilized to infer the effect of the alloying elements of an MN11 (Mg–1% Mn–1% Nd) alloy. The results support the hypothesis that selected rare earth intermetallic precipitates help to bring the CRSS values of basal and non-basal slip systems closer together, thus contributing to the reduced plastic anisotropy observed in these alloys