Evolution of microstructure and hardness in an AZ80 magnesium alloy processed by high-pressure torsion

The microstructure evolution during high pressure torsion and its influence on the mechanical properties of AZ80 magnesium alloy is presented in this study. Significant grain refinement was observed after high pressure torsion, while the homogeneity of the grain structure increases with the number of revolutions. Grain size decreases to about 50 nm after 15 revolutions. The microhardness profiles measured at through-thickness and through-width directions show no significant variation at different positions of the sample. Moreover, the negligible effect of the revolution number on the microhardness value was observed.

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Hardness Homogeneity in an AZ80 Magnesium Alloy Processed by High-Pressure Torsion

Materials Science Forum ◽

10.4028/www.scientific.net/msf.879.139 ◽

2016 ◽

Vol 879 ◽

pp. 139-144

Author(s):

Saad A. Alsubaie ◽

Yi Huang ◽

Terence G. Langdon

Keyword(s):

High Pressure ◽

Magnesium Alloy ◽

Room Temperature ◽

Vickers Microhardness ◽

High Pressure Torsion ◽

Disc Diameter ◽

Az80 Magnesium Alloy

Experiments were conducted on an AZ80 magnesium alloy by processing by high-pressure torsion (HPT) at room temperature (296 K) for up to 10 turns under an imposed pressure of 6.0 GPa. Measurements of the Vickers microhardness along diameters and through the disk thicknesses were recorded after HPT to evaluate the evolution towards homogeneity. The results show hardness increases up to a factor of approximately 2 and the deformation is more homogeneous along the disc diameter than through the thickness.

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Evolution of microstructure and hardness in Hf25Nb25Ti25Zr25 high-entropy alloy during high-pressure torsion

Journal of Alloys and Compounds ◽

10.1016/j.jallcom.2019.02.220 ◽

2019 ◽

Vol 788 ◽

pp. 318-328 ◽

Cited By ~ 8

Author(s):

Jenő Gubicza ◽

Anita Heczel ◽

Megumi Kawasaki ◽

Jae-Kyung Han ◽

Yakai Zhao ◽

...

Keyword(s):

High Pressure ◽

High Pressure Torsion ◽

High Entropy Alloy ◽

High Entropy ◽

Evolution Of Microstructure

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Microstructure and Microhardness of Copper Subjected to High Pressure Torsion

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.194-196.712 ◽

2011 ◽

Vol 194-196 ◽

pp. 712-715 ◽

Cited By ~ 1

Author(s):

Zi Ling Xie ◽

Lin Zhu Sun ◽

Fang Yang ◽

Xiao Bing Li

Keyword(s):

High Pressure ◽

High Pressure Torsion ◽

Type Equation ◽

Longitudinal Section ◽

Dislocation Cell ◽

Subgrain Structure ◽

Structure Morphology ◽

Evolution Of Microstructure ◽

Equiaxed Grains ◽

Variation Tendency

Experiments were conducted on copper subjected to High Pressure Torsion to investigate the evolution of microstructure and microhardness with shear strain, γ. Observations have been carried out in the longitudinal section for a proper demonstration of the structure morphology. An elongated dislocation cell/subgrain structure was observed at relatively low strain level. With increasing strain, the elongated subgrains transformed into elongated grains and finally into equiaxed grains with high angle grain boundaries. Measurements showed the hardness increases with increasing γ then tends to saturations when γ >5. The variation tendency of microhardness with γ can be simulated by Voce-type equation.

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Evolution of microstructure and hardness during artificial aging of an ultrafine-grained Al-Zn-Mg-Zr alloy processed by high pressure torsion

Journal of Materials Science ◽

10.1007/s10853-020-05264-4 ◽

2020 ◽

Vol 55 (35) ◽

pp. 16791-16805

Author(s):

Jenő Gubicza ◽

Moustafa El-Tahawy ◽

János L. Lábár ◽

Elena V. Bobruk ◽

Maxim Yu Murashkin ◽

...

Keyword(s):

High Pressure ◽

Dislocation Density ◽

Grain Boundaries ◽

Artificial Aging ◽

High Pressure Torsion ◽

Secondary Phase ◽

Aging Effect ◽

Angular Pressing ◽

Ultrafine Grained ◽

Evolution Of Microstructure

Abstract An ultrafine-grained (UFG) Al-4.8%Zn-1.2%Mg-0.14%Zr (wt%) alloy was processed by high pressure torsion (HPT) technique and then aged at 120 and 170 °C for 2 h. The changes in the microstructure due to this artificial aging were studied by X-ray diffraction and transmission electron microscopy. It was found that the HPT-processed alloy has a small grain size of about 200 nm and a high dislocation density of about 8 × 1014 m−2. The majority of precipitates after HPT are Guinier–Preston (GP) zones with a size of ~ 2 nm, and only a few large particles were formed at the grain boundaries. Annealing at 120 and 170 °C for 2 h resulted in the formation of stable MgZn2 precipitates from a part of the GP zones. It was found that for the higher temperature the fraction of the MgZn2 phase was larger and the dislocation density in the Al matrix was lower. The changes in the precipitates and the dislocation density due to aging were correlated to the hardness evolution. It was found that the majority of hardness reduction during aging was caused by the annihilation of dislocations and some grain growth at 170 °C. The aging effect on the microstructure and the hardness of the HPT-processed specimen was compared to that observed for the UFG sample processed by equal-channel angular pressing. It was revealed that in the HPT sample less secondary phase particles formed in the grain boundaries, and the higher amount of precipitates in the grain interiors resulted in a higher hardness even after aging.

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