Phase equilibria at 773 K and microwave absorbing properties of Er–Fe–Cr alloys

• The phase equilibria of Er–Fe–Cr system at 773 K were investigated experimentally.
• The isothermal section consists of 8 single-phase regions, 14 two-phase regions and 7 three-phase regions.
• The solid solubilities of Cr in ErFe2, ErFe3, Er6Fe23, Er2Fe17, and Fe at 773 K are determined by experimental method.
• The intermetallic compounds in Er–Fe–Cr system exhibit good microwave absorbing property in the X–band (8–12 GHz).

The phase equilibria of Er–Fe–Cr system at 773 K were investigated by X-ray powder diffraction (XRD), differential thermal analysis (DTA), and scanning electron microscopy (SEM) equipped with energy dispersive spectroscopy (EDS). The isothermal section consists of 8 single-phase regions, 14 two-phase regions and 7 three-phase regions. The homogeneity range of the ternary compound ErFe12−xCrx was determined to be x = 1.6–3.0. The maximum solid solubilities of Cr in ErFe2, ErFe3, Er6Fe23, Er2Fe17, and Fe are about 8.2, 1.2, 15.6, 9.6 and 13.8 at.% Cr, respectively, and the solubility limit of Fe in Cr is about 13.3 at.% Fe. The microwave absorbing properties of the intermetallic compounds in Er–Fe–Cr system were determined. All the samples exhibited good absorbing property in the X-band (8–12 GHz). With a coating thickness of d = 2.0 mm, the minimum return loss at the absorption peak frequency of the ErFe2, ErFe3, Er6Fe23, Er2Fe17 and ErFe10Cr2 are −19.66 dB at 9.6 GHz, −29.57 dB at 8.16 GHz, −35.04 dB at 12.72 GHz, −22.72 dB at 9.76 GHz and −13.51 dB at 11.2 GHz, respectively.