The New Materials Science Diffractometer STRESS-SPEC at FRM-II

Abstract

In response to the development of new materials and the application of materials and components in new technologies the direct measurement, calculation and evaluation of textures and residual stresses has gained worldwide significance in recent years. Non-destructive analysis for phase specific residual stresses and textures is only possible by means of diffraction methods. In order to cater for the development of these analytical techniques the new Materials Science Diffractometer STRESS-SPEC at FRM-II is designed to be equally applied to texture and residual stress analyses by virtue of its flexible configuration. The system compromises a highly flexible monochromator setup using three different monochromators: Ge (511), bent silicon (400) and pyrolitic graphite (PG). This range of monochromators and the possibility to vary the take-off angles from 2θM = 35º to 110º allows wavelength adjustment such that measurements can be performed around a scattering angle of 2θS ~ 90º. This is important in order to optimise neutron flux and resolution, especially for stress analysis on components, since the gauge volume element in that case is cubic and large vertical divergences due to focusing monochromators do not affect the spatial resolution. The instrument is now available for routine operation and here we will present details of recent experiments and instrument performance.

Strain Induced Martensitic Transformation in Austempered Ductile Iron (ADI)

“…The wavelength was set to 1.5483Å using a Ge (551) monochromator. Complete pole figures of ferrite (110) and (200), austenite (111) and (200) of the ADI samples were measured at the materials science diffactometer STRESS-SPEC [15] with a wavelength of 1.68Å using a Ge (311) monochromator. In the measurements the loading direction (LD) of the samples was perpendicularly to the incoming beam direction (figure 1).…”

Additional Phases at High Boron Content in High-Temperature Co–Re–Cr Alloys

“…The diffractometers SPODI [7,8], which is equipped with a bank of 80 position sensitive detector tubes, and Stress-Spec [9], equipped with a two-dimensional position sensitive detector, of Heinz Maier-Leibnitz-Zentrum (MLZ) at FRM II, Garching, Germany, were used for ND measurements. SPODI high-resolution neutron powder diffractometer covering the angular range (2θ) up to 154 • was used for precise determination of phase content at RT before in situ heating for all the samples.…”

A utilização da difração de neutrões na determinação do perfil de tensões residuais em revestimentos por soldadura

“…Este instrumento foi expressamente desenvolvido e projetado para o estudo da textura e das tensões residuais [4,12]. O instrumento está equipado com três monocromadores (grafite, germânio e silício), os quais permitem variar o comprimento de onda entre 0,1 nm e 0,24 nm, de modo a permitir obter ângulos de difração de 90º, tipicamente usados na determinação de tensões com feixe de neutrões para os principais materiais em aplicações de engenharia.…”