Jiansen Ni

Effect of Nb on the magnetic properties and microstructure for nanocomposite Nd2Fe14B∕α-Fe alloys by three-dimensional atom probe

The influence of Nb addition on the magnetic properties and microstructure for nanocomposite Nd9.5Fe79−xCo5NbxB6.5 (x=0,1,2,3) magnets was investigated. The results showed that Nb additon improved the coercivity obviously. An intergranular Nb–Fe–B phase with a chemical composition near the Nb:Fe:B stoichiometry of 1:2:1 between the Nd2Fe14B interface was found for Nd9.5Fe77Co5Nb2B6.5 by a three-dimensional atom probe technique, which provides direct evidence of the improvement of magnetic properties.

Behaviour of Membrane Construction Materials under Bi-Axial Tensile Loading

The aim of this research is to find a feasible method for the estimation of the tensile behaviour of woven membrane construction materials under bi-axial loading. During the model development, the woven membrane materials are treated as orthotropic, elastic and linear. Based on the constitutive relationships for orthotropic and elastic materials, two equations sets are deduced for the estimation of modulus in the warp and the fill direction respectively when suffering from the bi-axial loading. To checkout the validity of the estimation, seven groups of biaxial tensile tests with stress ratios of 1:0, 1:1, 2:1, 5:1, 1:2, 1:5 and 0:1 have been carried out on two kinds of PVCcoated woven membrane materials. From the comparison of the experiments and the prediction, it can be noticed that the model can achieve ideal results when it comes to the estimation of modulus in the leading direction, which is the direction with a higher stress than the other one. Therefore, based on the hypothesis of orthotropic, elastic and linear materials, there is an easy way to estimate the bi-axial tensile properties of woven membrane materials in the leading direction only through the uni-axial tensile tests.

Study on Two-Phase Nanocrystalline Nd2Fe14B/α-Fe Bonded Magnet

Two-phase nanocrystalline ribbons were prepared by melt-spun and subsequent heat treatment. Excellent magnetic properties of the bonded magnet were achieved as follows: Br = 0.67 T, JHc = 664.3 kA·m-1, (BH) max = 75.0 kJ·m-3. The mean grain size of the ribbons heat-treated at 710 °C/ 4 min is about 50 nm. After heat-treated the ribbons at 750 °C/ 4 min, the mean grain size is about 100 nm.