Neutron Diffraction News Today

The lack of magnetic refrigeration (MR) materials with high magnetocaloric effect (MCE) and large relative cooling power (RCP) in the temperature range required for hydrogen liquefaction (20 K–77 K) is a bottleneck for practical applications of MR cooling systems. The present investigation of TbMn2Si2-xGex compounds (x = 0.1, 0.2) by variable temperature neutron and synchrotron X-ray diffraction, magnetization and heat capacity measurements, establish that substitution of Si with Ge in TbMn2Si...

The thermal stability of ultrafine-grained metals can be fully understood when observing time-resolved microstructural changes over multiple-length scales. The global microstructural relaxation behavior upon heating of an ultrafine-grained (UFG) CoCrFeNi high-entropy alloy (HEA) was characterized by in-situ heating neutron diffraction measurements. Before heating, the nanocrystalline microstructure was introduced by applying high-pressure torsion (HPT), leading to severe lattice distortion by ex...

This report is aimed at giving an overview of the significance of the novel and innovative microstructural and microscopic characterization techniques for bulk nanostructured metals processed by severe plastic deformation, specifically high-pressure torsion (HPT). In practice, the microstructural relaxation behavior upon heating of nanostructured 316L stainless steel and CoCrFeNi high-entropy alloy was characterized by in-situ heating neutron diffraction measurements; the heterogeneous phase dis...

The major objective of this thesis was to explore an intelligent manufacturing method which is capable to fabricate high entropy alloys (HEAs) efficiently, and then to design new types of HEAs for use within a nuclear reactor environment. The microstructures, phase characterization and mechanical properties of alloys were investigated. Powder arc additive manufacturing (PAAM) having a high level of controlling local forming procedure was established to fabricate HEAs in-situ. This new manufactur...

This review summarizes the current knowledge on the α″ martensite transformation in metastable β Ti alloys under different stress state conditions gained using various in situ techniques that range from the meso- to the nanoscale. Compared to ex situ observations, in situ observation can be conducted on a single region while changing external stimuli, and are therefore capable of elucidating the interim microstructural evolution. The strengths and shortcomings of different techniques to give...

The structural and magnetic properties of LaMn2Ge2 compound in both the as-cast bulk and melt-spun ribbon forms have been investigated by a comprehensive set of x-ray/neutron powder diffraction, magnetic and heat capacity measurements as well as corresponding sets of data analyses. Our neutron diffraction study reveals that with decreasing temperature the magnetic state of bulk LaMn2Ge2 changes first from paramagnetic to incommensurate antiferromagnetism AFfs at TN ~ 430 K, and then gives way to...

In recent years, twin wire-arc additive manufacturing (T-WAAM) technique has been considered as a promising method of fabricating and shaping titanium aluminide components with high efficiency and low cost. However, excessive thermal input of the non-consumable tungsten electrode arc deposition induces significant residual stresses in the buildup component, thus accurate measurement of residual stresses is necessary for T-WAAM buildup part quality assessment. In the present research, non-destruc...

Abstract Functionally graded material has been increasingly attractive due to the locally designed and optimized material properties. In the present paper, to achieve high thermal lattice structural stability and high corrosion resistance in each side of one bulk material, an Fe Ni–FeNi compositionally graded material (FGM) bulk sample has been fabricated using an innovative wire-arc additive manufacturing process. A subsequent homogenization post-production heat treatment is applied to stabi...

This study investigates the phase transformation and microstructure of porous FeAl parts sintered from elemental powder mixtures using in-situ neutron diffraction and in-situ thermal dilatometry. A single B2 structured FeAl phase was determined in the sintered FeAl alloy. The combined effects of the Kirkendall porosity, transient liquid phase, and phase transformations associated with powder sintering all contribute to the swelling phenomenon of the final sintered part. The aqueous corrosion tes...