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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 TbMn2Si2 leads to a significant enlargement of the unit cell and modification of the magnetic properties. T...

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 excess dislocations and defects. The sequential information on the structural relaxation of recovery, ...

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 distribution of an HPT-bonded hetero-nanostructured AlMg alloy was examined using synchrotron high-ener...

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 manufacturing process possesses time and cost saving, and rapid cooling rate which can reduce the segregation ...

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 insight into the martensitic transformation are identified. Both the formation of α″ martensite ...