Effect of mechanical alloying and SPS process on microstructure and properties of FeCrAl alloys
FeCrAl alloys have excellent high temperature mechanical properties,radiation resistance and high temperature corrosion resistance,and are considered as one of the ideal candidate materials for advanced fission reactor structures and fault tolerant cladding,and have become a research hotspot in the field of nuclear materi-als. In order to further optimize the process and improve the properties of FeCrAl alloys,the influencing factors of mechanical alloying and the spark plasma sintering (SPS) on the densification degree and microstructure of Fe-CrAl alloys were systematically studied in this paper,and the Rockwell hardness,static room temperature tensile properties and high temperature tensile properties of fully densified specimens were further tested. The results show that Alloy0 (FeCrAl alloys),Alloy1 (FeCrAl--0.2Re alloys),and Alloy2 (FeCrAl-0.2Nd-0.2Hf alloys) alloy powder are mixed uniformly and obviously alloyed. Through orthogonal experiments,the optimal SPS process parameters are sintering temperature 1 060 ℃,sintering pressure 50 MPa and holding time 5 min,the samples can be full densifying,and the density reached 99.8％,99.9％ and 99.9％,respectively. The main phases of the three alloys are Fe-Cr,Al-Cr and Fe-Al alloy phases,and the main phases are Fe-Cr alloys. The average grain siz-es of Alloy0 and Alloy1 are (12.2±5.8) μm and (9.82±3.2) μm,respectively. In addition to the finer equiaxial crystals,more dispersed columnar crystals are formed in Alloy2 alloy. The microstructure of the three alloys is mainly the second phase rich in Al with larger particles distributed in the crystal and the second phase with Fe-Cr as the main part. The properties of Alloy0,Alloy1 and Alloy2 alloys are significantly improved,and the op-timal Rockwell hardness of Alloy0,Alloy1 and Alloy2 alloys is (64.60±1.1) HRC,(66.53±2.3) HRC and(64.51±2.5) HRC,and the tensile strength at room temperature is (626±12)MPa,(661±5)MPa and (685±10) MPa,respectively. The elongation of this allloy are 9.0％±0.5％,8.8％±0.2％ and 10％±0.9％,respectively,and the mechanical properties at high temperature are also significantly improved. Mechanical alloying and SPS are effective processes to improve the properties of alloys.
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