Structure and mechanical properties of a low-density AlCrFeTi medium entropy alloy produced by spark plasma sintering

MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING

卷:795

Article

Shaysultanov, D.¹  Nepapushev, A.²  Zherebtsov, S.¹  Moskovskikh, D.²  Stepanov, N.¹ 

[1] Belgorod Natl Res Univ, Lab Bulk Nanostruct Mat, Pobeda 85, Pobeda 308015, Russia

[2] Natl Univ Sci & Technol, Ctr Funct Nanoceram, Leninskiy Prospekt 4, Moscow 119049, Russia

关键词: Medium entropy alloys;    Mechanical alloying;    Spark plasma sintering;    Microstructure;    Mechanical properties;    Phase stability;   

DOI  :  10.1016/j.msea.2020.140018

来源: Elsevier

【 摘 要 】

Bulk equiatomic AlCrFeTi medium entropy alloy was produced by mechanical alloying (MA) and spark plasma sintering (SPS). Powders with a homogeneous chemical composition composed of amorphous and bcc phases were obtained due to MA. Bulk, almost porosity free specimen of the alloy with the measured density of 5.53 +/- 0.07 g x cm(-3) was obtained after SPS. A mixture of a (Fe, Ti)-rich C14 Laves phase, a Cr-rich bcc phase, and an Al-rich L1(2) phase was found in the as-sintered specimens. The average size of grains/particles of the different phases was 115 +/- 100 nm. Annealing at 1000 degrees C resulted in some coarsening of the microstructure to the grain/particle size of 140 +/- 120 nm and in an increase in the fraction of the bcc and L1(2) phases, yet the microstructure was found to be relatively stable. After SPS the AlCrFeTi alloy had a high microhardness of 1090 +/- 120 HV, which decreased after annealing to 870 +/- 70 HV. Compression tests have meanwhile revealed low ductility of the alloy after SPS - the alloy exhibited brittle fracture at room temperature and became ductile at only 800 degrees C. After annealing the alloy demonstrated reasonable ductility already at 700 degrees C. Also, the annealed alloy had a remarkable specific yield strength of 258 kPa x m(3)/kg at 700 degrees C. The experimental data on the phase composition of the alloy was compared with the Thermo-Calc predictions, and the relationships between the structure and properties of the alloy were discussed.

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