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High Ga-doped heavy rare earth free sintered Nd‒Fe‒B magnets with the different boron contents (mass fraction) were prepared by powder metallurgy method in this work. The effect of boron content on phase formation, microstructure, and magnetic properties of the magnets was investigated. Results show that the coercivity of the Ga-doped sintered Nd‒Fe‒B magnets decreases as the boron content increases from 0.90% to 1.00%. The magnetic properties deteriorate drastically when the boron content exceeds 0.94%. Microstructure studies show that the significant amount of Nd6Fe13Ga phases are present and the grain boundary broadens when the boron content is low. The increase of boron content inhibits the formation of Nd6Fe13Ga phase, which leads to the transformation of grain boundary from non-ferromagnetic to ferromagnetic and the volume fraction decrease of the grain boundary phase. Further micromagnetics simulation confirms that the construction of the non-ferromagnetic grain boundary phase and the wider grain boundary phase can reduce the exchange-coupling interaction between the Nd2Fe14B main phase grains, which is critical to ensure the high coercivity of the magnets.

C51H79O11Y, monoclinic, P21/c (no. 14), a = 8.8682(3) Å, b = 22.1328(8) Å, c = 27.9848(10) Å, β = 96.710(1)°, V = 5455.2(3) Å3, Z = 4, Rgt(F) = 0.0495, wRref(F2) = 0.1275, T = 296(2) K.

C51H79O11Y, monoclinic, P21/c (no. 14), a = 8.8682(3) Å, b = 22.1328(8) Å, c = 27.9848(10) Å, β = 96.710(1)°, V = 5455.2(3) Å3, Z = 4, Rgt(F) = 0.0495, wRref(F2) = 0.1275, T = 296(2) K. [ABSTRACT FROM AUTHOR]

Objective: To explore the diagnostic value of the system serial of three-dimensional spoiled gradient-echo T1-weighted MR imaging (three-dimensional volumetric interpolated breath-hold examination, 3D-VIBE) used to the preoperative assessment of hepatic portal cholangiocarcinoma., Methods: 31 surgically confirmed patients with hepatic portal cholangiocarcinoma underwent the preoperative examination through MR imaging system serial that was including T2W, two dimension (2D) T1W plain scan, 2D magnetic resonance cholangiopancreatography (MRCP), and Gadolinium-enhanced 3D-VIBE triple-phase dynamic acquisitions followed by 2D T1W scanning at the equilibrium phase. Meanwhile, it was performed for focusing on assessing or judging the tumor morphological type, the longitudinal infiltration extent of the bile duct and the involvement of neighbor blood vessels. And the 3D-VIBE was compared with 2D T1W systems for assessing or judging the tumor resectability., Results: (1) (3D-VIBE directly displayed the hepatic portal tumors and correctly classified the tumor morphological types in all patients, but 2D T1W systems missed to show 8 hepatic portal cholangiocarcinoma of periductal-infiltrating type (25. 8%); (2) According to Bismuth-Corlette classification, 3D-VIBE was closed to MRCP in accuracy (93.5%) for showing the longitudinal infiltration extent of tumor, but 2D T1W system serial underestimated (32.3%) the extent. (3) 3D-VIBE showed more involvement of the main trunk of hepatic artery, portal vein and their branches than 2D T1W systems did. (4) The positive predicting value and accuracy for assessing tumor resectability were 84.0% and 90.0% for 3D-VIBE system, as 64.0% and 71.0% for 2D T1W systems., Conclusion: 3D-VIBE system is superior to other MR imaging system serial in the preoperative assessment of the morphological type, the longitudinal infiltration extent and the tumor resectability of hepatic portal cholangiocarcinoma.