Excellent room temperature ductility of as-cast TRIP high-entropy alloy via Mo and C alloying

2019 ◽  
Vol 55 (5) ◽  
pp. 2239-2244 ◽  
Author(s):  
Yukun Lv ◽  
Xuerou Zhao ◽  
Tuo Shi ◽  
Li Bai ◽  
Jian Chen ◽  
...  
2015 ◽  
Vol 645 ◽  
pp. 255-263 ◽  
Author(s):  
J.-Ph. Couzinié ◽  
L. Lilensten ◽  
Y. Champion ◽  
G. Dirras ◽  
L. Perrière ◽  
...  

Metals ◽  
2019 ◽  
Vol 9 (12) ◽  
pp. 1351 ◽  
Author(s):  
Evgeniya Panina ◽  
Nikita Yurchenko ◽  
Sergey Zherebtsov ◽  
Nikita Stepanov ◽  
Gennady Salishchev ◽  
...  

The effect of laser beam welding on the structure and properties of a Ti1.89NbCrV0.56 refractory high entropy alloy was studied. In particular, the effect of different pre-heating temperatures was examined. Due to the low ductility of the material, laser beam welding at room temperature resulted in the formations of hot cracks. Sound butt joints without cracks were produced using pre-heating to T ≥ 600 °C. In the initial as-cast condition, the alloy consisted of coarse bcc grains with a small amount of lens-shaped C15 Laves phase particles. A columnar microstructure was formed in the welds; the thickness of the grains increased with the temperature of pre-heating before welding. The Laves phase particles were formed in the seams after welding at 600 °C or 800 °C, however, these particles were not observed after welding at room temperature or at 400 °C. Soaking at elevated temperatures did not change the microstructure of the base material considerably, however, “additional” small Laves particles formed at 600 °C or 800 °C. Tensile test of welded specimens performed at 750 °C resulted in the fracture of the base material because of the higher hardness of the welds. The latter can be associated with the bcc grains refinement in the seams.


MRS Advances ◽  
2017 ◽  
Vol 2 (27) ◽  
pp. 1429-1434 ◽  
Author(s):  
Katsushi Tanaka ◽  
Takeshi Teramoto ◽  
Ryo Ito

ABSTRACTMono-crystalline elastic constants of equiatomic quinary Cr-Mn-Fe-Co-Ni high entropy alloy with the fcc structure have experimentally been determined by a resonance ultrasound spectroscopy at room temperature. The values of the bulk modulus of the high entropy alloy experimentally determined are similar to other conventional fcc metals when the values are normalized by the melting points. This indicates that the entropy change at melting is similar to that of conventional metals. The values of Pough’s index and the Cauchy pressure are determined as 1.79 and -11.6 GPa, respectively. When the ductility of the alloy is judged from the indices, the ductility of the high entropy alloy is limited. In order to explain the negative Cauchy pressure of the high entropy alloy, it is required to assume that relatively strong directional interatomic bondings like intermetallic compounds exist in the alloy though the crystal is disordered solid solution.


2021 ◽  
Vol 22 (4) ◽  
pp. 687-696
Author(s):  
Sachin Rai ◽  
Navin Chaurasiya ◽  
Pramod K. Yadawa

Consequent to the interaction potential model, the high-order elastic constants at high entropy alloys in single-phase quaternary ScTiZrHf have been calculated at different temperatures. Elastic constants of second order (SOECs) helps to determine other ultrasonic parameters. With the help of SOECs other elastic moduli, bulk modulus, shear modulus, Young’s modulus, Pugh’s ratio, elastic stiffness constants and Poisson’s ratio are estimated at room temperature for elastic and mechanical characterization. The other ultrasonic parameters are calculated at room temperature for elastic and mechanical characterization. The temperature variation of ultrasonic velocities along the crystal's z-axis is evaluated using SOECs. The temperature variation of the  average debye velocity and the thermal relaxation time (τ) are also estimated along this orientation axis. The ultrasonic properties correlated with elastic, thermal and mechanical properties which is temperature dependent is also discussed. The ultrasonic attenuation due to phonon – phonon (p-p) interactions is also calculated at different temperatures. In the study of ultrasonic attenuation such as a function of temperature, thermal conductivity appears to be main contributor and p- p interactions are the responsible reason of attenuation and found that the mechanical properties of the high entropy alloy ScTiZrHf are superior at room temperature.


2020 ◽  
Vol 178 ◽  
pp. 387-390 ◽  
Author(s):  
Parisa Edalati ◽  
Ricardo Floriano ◽  
Abbas Mohammadi ◽  
Yongtao Li ◽  
Guilherme Zepon ◽  
...  

2016 ◽  
Vol 849 ◽  
pp. 76-84 ◽  
Author(s):  
Yan Zhang ◽  
Yuan Liu ◽  
Yan Xiang Li ◽  
Xiang Chen ◽  
Hua Wei Zhang

A new refractory alloy HfNbSi0.5TiVZr was synthesized by induction levitation melting with the aim to achieve an excellent strength and toughness balance of the Hf-Nb-Ti-Zr based alloy. The as-cast alloy with density of ρ=7.75g/cm3 and microhardness of Hv=464 had the microstructure consisting of bcc solid solution with little vanadium rich phase and fine intermetallic phase presented dendritic structure. Mixing entropy and formation enthalpy can explain this behavior. After heat treatment at 1373K for 4 h, no new phase come into being but elements solute more fully. Compressive yield strength of the alloy gradually decreased from 1540MPa at room temperature to 371MPa at 1073K in as-cast state and decreased from 1483MPa at room temperature to 102MPa at 1073K after annealed. Comparing with the similar high entropy alloys, the structure combining silicide and continuous solid phase have a great benefit to the balance of strength and ductility.


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