- Email: [email protected]
Neutron diffraction facilities at the high flux reactor, Petten
Physica B 276}278 (2000) 160}161
Neutron di!raction facilities at the high #ux reactor, Petten C. Ohms *, A.G. Youtsos , A. Bontenbal, F.M. Mulder JRC, P.O.Box 2, 1755ZG Petten, The Netherlands NRG, P.O.Box 1, 1755ZG Petten, The Netherlands IRI, Delft University of Technology, Mekelweg 15, 2629JB Delft, The Netherlands
Abstract The High Flux Reactor in Petten is equipped with twelve beam tubes for the extraction of thermal neutrons for applications in materials and medical science. Beam tubes HB4 and HB5 are equipped with di!ractometers for residual stress and powder investigations. Recently at HB4 the Large Component Neutron Di!raction Facility has been installed. It is a unique facility with respect to its capability of handling heavy components up to 1000 kg in residual stress testing. Its basic features are described and the "rst applications on thick piping welds are shown. The di!ractometer at HB5 can be set up for powder and stress measurements. Recent applications include temperature dependent measurements on phase transitions in intermetallic compounds and on Li ion energy storage materials. 2000 Elsevier Science B.V. All rights reserved. Keywords: Residual stress; Powder di!ractometer; Welds; Magnetic transitions
1. The Large Component Neutron Di4raction Facility (LCNDF) In the process of upgrading the HFR neutron di!raction facilities [1] it was decided to develop a new instrument for stress testing heavy structural components. Its objectives are mapping of residual stresses for adequate life assessment of components, and the micro-structural and residual stress characterization for adequate development of new composite materials. The LCNDF has become a unique European instrument in terms of its weight-handling capacity. The maximum translations are 400 mm horizontally (2;) and 300 mm vertically with a spatial resolution of up to 0.01 mm. The full weight can be supported up to 300 mm o! the instrument central axis. This has been achieved through the physical separation of the detector rotation axis (2h) from the specimen rotation axis (u). Applicable gauge sizes range from 1 mm to 2 cm.
* Corresponding author. Tel.: #31-224-565012; fax: #31224-561449. E-mail address: [email protected] (C. Ohms)
Since the LCNDF has been in operation two nuclear piping welds have been tested. Fig. 1 shows a thickwalled austenitic piping weld with a diameter of &430 mm and a weight of &350 kg on the facility. The tests have been performed mainly in the heat a!ected zone and some results are given in Ref. [2]. In a second campaign three-dimensional stress mapping has been performed across a bi-metallic ferritic-austenitic steel nuclear piping weld.
2. The combined powder and stress di4ractometer at HB5 The di!ractometer operates at a wavelength of 0.258 nm and a #ux of 10 cm\s\ at the sample position. The angular resolution is d2h"0.63 at 2h"763, and the 2h angular range is 5}1553. A cryostat with a threestage closed cycle helium cooling system has been installed for temperatures between 3.6 K and room temperature. Ovens can be used for temperatures up to 1800 K. As an example of di!raction performed at HB5 a result is shown on the Li depleted spinel compound Li [Mn Li ]O that can act as cathode material in a charged Li battery. It was found to have a cubic structure down to temperatures of 4 K in contrast with
0921-4526/00/$ - see front matter 2000 Elsevier Science B.V. All rights reserved. PII: S 0 9 2 1 - 4 5 2 6 ( 9 9 ) 0 1 2 9 8 - 3
C. Ohms et al. / Physica B 276}278 (2000) 160}161
Fig. 1. The LCNDF in operation testing a 350 kg thick walled nuclear piping weld
161
the &"lled' stoichiometric compound LiMn O that has a Jahn}Teller transition [3,4]. Below 25 K antiferromagnetic ordering sets in. The 4 K spectrum in Fig. 2 of Li [Mn Li ]O was indexed with a cubic unit cell having a magnetic propagation vector (1/2,1/2,1/2) [5]. This clearly indicates that the structure is cubic at 4 K with a doubled a-axis. Another example is the structure determination of the low-temperature phase in the Heusler alloy UNi Sn. At 293 K the structure is cubic while below 130 K the symmetry is lowered. The low-temperature structure was found to be orthorhombic [6,7] and might be the key to the unknown structure of a number of chemically related Heusler alloys. The structure has recently been con"rmed in detail at the high-resolution powder di!ractometer at ISIS [8]. It can be concluded that with the LCNDF and the Combined Powder and Stress Di!ractometer there are strong tools available at the HFR for materials characterization in terms of residual stress and (micro-) structure. References
Fig. 2. Spectrum of Li [Mn Li ]O at 4 K. The nuclear peaks are at angles above 603, while the magnetic peaks are at lower angles. The inset gives a 10;vertical magni"cation. Indexing the magnetic peaks shows doubling of the cubic unit cell by the antiferromagnetic ordering. There is no symmetry lowering Jahn}Teller transition.
[1] C. Ohms, A.G. Youtsos, in: T. Ericsson, et al. (Eds.), Proceedings of ICRS-5, Vol. 2, LinkoK ping University, Sweden, 1997, pp. 738}743. [2] C. Ohms, A.G. Youtsos, in: U. von Estor!, et al., (Eds.), Proceedings of the Joint EC IAEA Specialists Meeting on NDT Methods for Monitoring Degradation, European Communities, 1999, pp. 38}42. [3] J. Rodriquez-Caravajal et al., Phys. Rev. Lett 81 (1998) 4660. [4] Young Yoo Lee et al., J. Am. Chem. Soc 120 (1998) 12601. [5] V.W.J. Verhoeven et al., to be published. [6] A. Drost et al., Solid State Commun 88 (1993) 327. [7] F.M. Mulder et al., Phys. Rev. Lett 77 (1996) 3477. [8] F.M. Mulder et al., Physica B 262 (1999) 312.
Neutron di!raction facilities at the high #ux reactor, Petten C. Ohms *, A.G. Youtsos , A. Bontenbal, F.M. Mulder JRC, P.O.Box 2, 1755ZG Petten, The Netherlands NRG, P.O.Box 1, 1755ZG Petten, The Netherlands IRI, Delft University of Technology, Mekelweg 15, 2629JB Delft, The Netherlands
Abstract The High Flux Reactor in Petten is equipped with twelve beam tubes for the extraction of thermal neutrons for applications in materials and medical science. Beam tubes HB4 and HB5 are equipped with di!ractometers for residual stress and powder investigations. Recently at HB4 the Large Component Neutron Di!raction Facility has been installed. It is a unique facility with respect to its capability of handling heavy components up to 1000 kg in residual stress testing. Its basic features are described and the "rst applications on thick piping welds are shown. The di!ractometer at HB5 can be set up for powder and stress measurements. Recent applications include temperature dependent measurements on phase transitions in intermetallic compounds and on Li ion energy storage materials. 2000 Elsevier Science B.V. All rights reserved. Keywords: Residual stress; Powder di!ractometer; Welds; Magnetic transitions
1. The Large Component Neutron Di4raction Facility (LCNDF) In the process of upgrading the HFR neutron di!raction facilities [1] it was decided to develop a new instrument for stress testing heavy structural components. Its objectives are mapping of residual stresses for adequate life assessment of components, and the micro-structural and residual stress characterization for adequate development of new composite materials. The LCNDF has become a unique European instrument in terms of its weight-handling capacity. The maximum translations are 400 mm horizontally (2;) and 300 mm vertically with a spatial resolution of up to 0.01 mm. The full weight can be supported up to 300 mm o! the instrument central axis. This has been achieved through the physical separation of the detector rotation axis (2h) from the specimen rotation axis (u). Applicable gauge sizes range from 1 mm to 2 cm.
* Corresponding author. Tel.: #31-224-565012; fax: #31224-561449. E-mail address: [email protected] (C. Ohms)
Since the LCNDF has been in operation two nuclear piping welds have been tested. Fig. 1 shows a thickwalled austenitic piping weld with a diameter of &430 mm and a weight of &350 kg on the facility. The tests have been performed mainly in the heat a!ected zone and some results are given in Ref. [2]. In a second campaign three-dimensional stress mapping has been performed across a bi-metallic ferritic-austenitic steel nuclear piping weld.
2. The combined powder and stress di4ractometer at HB5 The di!ractometer operates at a wavelength of 0.258 nm and a #ux of 10 cm\s\ at the sample position. The angular resolution is d2h"0.63 at 2h"763, and the 2h angular range is 5}1553. A cryostat with a threestage closed cycle helium cooling system has been installed for temperatures between 3.6 K and room temperature. Ovens can be used for temperatures up to 1800 K. As an example of di!raction performed at HB5 a result is shown on the Li depleted spinel compound Li [Mn Li ]O that can act as cathode material in a charged Li battery. It was found to have a cubic structure down to temperatures of 4 K in contrast with
0921-4526/00/$ - see front matter 2000 Elsevier Science B.V. All rights reserved. PII: S 0 9 2 1 - 4 5 2 6 ( 9 9 ) 0 1 2 9 8 - 3
C. Ohms et al. / Physica B 276}278 (2000) 160}161
Fig. 1. The LCNDF in operation testing a 350 kg thick walled nuclear piping weld
161
the &"lled' stoichiometric compound LiMn O that has a Jahn}Teller transition [3,4]. Below 25 K antiferromagnetic ordering sets in. The 4 K spectrum in Fig. 2 of Li [Mn Li ]O was indexed with a cubic unit cell having a magnetic propagation vector (1/2,1/2,1/2) [5]. This clearly indicates that the structure is cubic at 4 K with a doubled a-axis. Another example is the structure determination of the low-temperature phase in the Heusler alloy UNi Sn. At 293 K the structure is cubic while below 130 K the symmetry is lowered. The low-temperature structure was found to be orthorhombic [6,7] and might be the key to the unknown structure of a number of chemically related Heusler alloys. The structure has recently been con"rmed in detail at the high-resolution powder di!ractometer at ISIS [8]. It can be concluded that with the LCNDF and the Combined Powder and Stress Di!ractometer there are strong tools available at the HFR for materials characterization in terms of residual stress and (micro-) structure. References
Fig. 2. Spectrum of Li [Mn Li ]O at 4 K. The nuclear peaks are at angles above 603, while the magnetic peaks are at lower angles. The inset gives a 10;vertical magni"cation. Indexing the magnetic peaks shows doubling of the cubic unit cell by the antiferromagnetic ordering. There is no symmetry lowering Jahn}Teller transition.
[1] C. Ohms, A.G. Youtsos, in: T. Ericsson, et al. (Eds.), Proceedings of ICRS-5, Vol. 2, LinkoK ping University, Sweden, 1997, pp. 738}743. [2] C. Ohms, A.G. Youtsos, in: U. von Estor!, et al., (Eds.), Proceedings of the Joint EC IAEA Specialists Meeting on NDT Methods for Monitoring Degradation, European Communities, 1999, pp. 38}42. [3] J. Rodriquez-Caravajal et al., Phys. Rev. Lett 81 (1998) 4660. [4] Young Yoo Lee et al., J. Am. Chem. Soc 120 (1998) 12601. [5] V.W.J. Verhoeven et al., to be published. [6] A. Drost et al., Solid State Commun 88 (1993) 327. [7] F.M. Mulder et al., Phys. Rev. Lett 77 (1996) 3477. [8] F.M. Mulder et al., Physica B 262 (1999) 312.