摘要
The microstructures and defects of various aged Sm( Co, Fe,Cu,Ti)_7 alloys have been observed in several orientations by using high resolution electron microscopy.Experimental results indicate that the alloy is composed of Sm2(Co,Fe,Cu,Ti)_(17)(2:17) phase with a small amount of titanium and Sm(Co,Fe,Cu)5,(1:5) phase.The 2:17 phase is rich in iron and the 1.5 phase is rich in copper.At aging stages corresponding to the peak magnetic coercivity,the alloy has a cellular-like microstructure with fine cells of the 2:17 phase surrounded by thin boundaries of the 1:5 phase.The average size of the cells is about 33 nm.The orientation relationship of [0001]_(2:17)/[0001]1:5 and(1210)_(2:17)/(0110)_(1:5) has been found in this alloy.The high resolution images show coherence between 2:17 phase and 1:5 phase and very small mismatch in some phase boundaries.The cells of 2:17 phase are full of microtwins with twin plane perpendicular to caxis.The cells of 2:17 phase rapidly grow up,when the aging temperature rises and aging time prolongs.For the alloy aged at 850℃, the 2:17 phase and 1:5 phase transform from cellular-like into striplike microstructure,and a few of twin boundaries can be seen in the 2:17 phase.Besides the twin boundaries,antiphase boundaries are sometimes observed in the 2:17 phase of the alloy aged at 800℃,for 10 h.
The microstructures and defects of various aged Sm( Co, Fe,Cu,Ti)_7 alloys have been observed in several orientations by using high resolution electron microscopy.Experimental results indicate that the alloy is composed of Sm2(Co,Fe,Cu,Ti)_(17)(2:17) phase with a small amount of titanium and Sm(Co,Fe,Cu)5,(1:5) phase.The 2:17 phase is rich in iron and the 1.5 phase is rich in copper.At aging stages corresponding to the peak magnetic coercivity,the alloy has a cellular-like microstructure with fine cells of the 2:17 phase surrounded by thin boundaries of the 1:5 phase.The average size of the cells is about 33 nm.The orientation relationship of [0001]_(2:17)/[0001]1:5 and(1210)_(2:17)/(0110)_(1:5) has been found in this alloy.The high resolution images show coherence between 2:17 phase and 1:5 phase and very small mismatch in some phase boundaries.The cells of 2:17 phase are full of microtwins with twin plane perpendicular to caxis.The cells of 2:17 phase rapidly grow up,when the aging temperature rises and aging time prolongs.For the alloy aged at 850℃, the 2:17 phase and 1:5 phase transform from cellular-like into striplike microstructure,and a few of twin boundaries can be seen in the 2:17 phase.Besides the twin boundaries,antiphase boundaries are sometimes observed in the 2:17 phase of the alloy aged at 800℃,for 10 h.
