Activation Enthalpies of Deformation-Induced Lattice Defects in Severe Plastic Deformation Nanometals Measured by Differential Scanning Calorimetry

2009 ◽  
Vol 41 (4) ◽  
pp. 810-815 ◽  
Author(s):  
Daria Setman ◽  
Michael B. Kerber ◽  
Erhard Schafler ◽  
Michael J. Zehetbauer
2008 ◽  
Vol 584-586 ◽  
pp. 255-260 ◽  
Author(s):  
Nong Gao

Differential Scanning Calorimetry (DSC) is a thermal analysis technique that measures the energy absorbed or released by a sample as a function of temperature or time. DSC has wide application for analysis of solid state reactions and solid-liquid reactions in many different materials. In recent years, DSC has been applied to analyze materials and alloys processed through Severe Plastic Deformation (SPD). The basic principle of SPD processing is that a very high strain is introduced into materials which achieve significant grain refinement and improve properties of materials. This review paper presents some recent examples of the applications of DSC for materials subjected to SPD, especially by Equal-Channel Angular Pressing and High-Pressure Torsion.


Micromachines ◽  
2020 ◽  
Vol 11 (4) ◽  
pp. 339 ◽  
Author(s):  
Amir Noori ◽  
Mattia Bartoli ◽  
Alberto Frache ◽  
Erik Piatti ◽  
Mauro Giorcelli ◽  
...  

In this research paper, we reported the synthesis of biochar-based composites using biochar derived from exhausted tea leaves and polypropylene. The resulting materials were deeply characterized investigating mechanical (dynamic mechanical thermal analysis), thermal (thermogravimetrical analysis and differential scanning calorimetry), morphological (field emission scanning microscopy) and electrical properties vs. temperature. Furthermore, electrical conductivity was studied for a wide range of pressures showing an irreversible plastic deformation. An increment of one order of magnitude in the conductivity was observed in the case of 40 wt% biochar loading, reaching a value of 0.2 S/m. The material produced exhibited the properties of an irreversible pressure sensor.


2018 ◽  
Vol 45 (3) ◽  
pp. 79-86 ◽  
Author(s):  
V.A. Zhorin ◽  
M.R. Kiselev

Mixtures of polyethylene and 80% germanium dioxide, magnesium, magnesium oxide, and sodium chloride were subjected to plastic deformation under a pressure of 0.5–4.0 GPa, and were then investigated by differential scanning calorimetry. The enthalpy of melting of the polymer in certain mixtures reached 300 J/g. On thermograms of deformed mixtures, exothermic processes were observed. The observed thermal effects are possibly due to interphase interaction at the phase boundary.


Materials ◽  
2019 ◽  
Vol 12 (17) ◽  
pp. 2670
Author(s):  
Alexander Glezer ◽  
Nikolay Sitnikov ◽  
Roman Sundeev ◽  
Alexander Shelyakov ◽  
Irina Khabibullina

In recent years, the methods of severe plastic deformation and rapid melt quenching have proven to be an effective tool for the formation of the unique properties of materials. The effect of high-pressure torsion (HPT) on the structure of the amorphous alloys of the quasi-binary TiNi–TiCu system with a copper content of more than 30 at.% produced by melt spinning technique has been analyzed using the methods of scanning electron microscopy, X-ray diffraction analysis, and differential scanning calorimetry (DSC). The structure examinations have shown that the HPT of the alloys with a Cu content ranging from 30 to 40 at.% leads to nanocrystallization from the amorphous state. An increase in the degree of deformation leads to a substantial change in the character of the crystallization reflected by the DSC curves of the alloys under study. The alloys containing less than 34 at.% Cu exhibit crystallization peak splitting, whereas the alloys containing more than 34 at.% Cu exhibit a third peak at lower temperatures. The latter effect suggests the formation of regions of possible low-temperature crystallization. It has been established that the HPT causes a significant decrease in the thermal effect of crystallization upon heating of the alloys with a high copper content relative to that of the initial amorphous melt quenched state.


Materials ◽  
2019 ◽  
Vol 12 (10) ◽  
pp. 1611 ◽  
Author(s):  
Yue Dong ◽  
Suya Liu ◽  
Johannes Biskupek ◽  
Qingping Cao ◽  
Xiaodong Wang ◽  
...  

The effect of severe plastic deformation by high-pressure torsion (HPT) on the structure and plastic tensile properties of two Zr-based bulk metallic glasses, Zr55.7Ni10Al7Cu19Co8.3 and Zr64Ni10Al7Cu19, was investigated. The compositions were chosen because, in TEM investigation, Zr55.7Ni10Al7Cu19Co8.3 exhibited nanoscale inhomogeneity, while Zr64Ni10Al7Cu19 appeared homogeneous on that length scale. The nanoscale inhomogeneity was expected to result in an increased plastic strain limit, as compared to the homogeneous material, which may be further increased by severe mechanical work. The as-cast materials exhibited 0.1% tensile plasticity for Zr64Ni10Al7Cu19 and Zr55.7Ni10Al7Cu19Co8.3. Following two rotations of HPT treatment, the tensile plastic strain was increased to 0.5% and 0.9%, respectively. Further testing was performed by X-ray diffraction and by differential scanning calorimetry. Following two rotations of HPT treatment, the initially fully amorphous Zr55.7Ni10Al7Cu19Co8.3 exhibited significantly increased free volume and a small volume fraction of nanocrystallites. A further increase in HPT rotation number did not result in an increase in plastic ductility of both alloys. Possible reasons for the different mechanical behavior of nanoscale heterogeneous Zr55.7Ni10Al7Cu19Co8.3 and homogeneous Zr64Ni10Al7Cu19 are presented.


2008 ◽  
Vol 584-586 ◽  
pp. 355-360 ◽  
Author(s):  
Daria Setman ◽  
Maciej Krystian ◽  
Michael Zehetbauer

Pure palladium (99.95%) was hydrogenated, subsequently deformed by High Pressure Torsion (HPT) and analyzed by differential scanning calorimetry (DSC). For comparison some hydrogen-free HPT processed samples were also investigated. In case of the hydrogenated HPT Pd, the concentration of single / double vacancies is noticeably higher. The importance of hydrogen for the formation and stabilization of vacancy type defects and dislocations is discussed.


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