Ferromagnetic element microalloying and clustering effects in high B_s Fe-based amorphous alloys

Fe83（Cox,Niy）（B11Si2P3C1）1-x,y/17（x,y=1–3）amorphous alloys with high saturation magnetic flux density（Bs）and excellent soft-magnetic properties were developed and then the microalloying and clustering effects were explored.The microalloying of Co and Ni improves the Bsfrom 1.65 T to 1.67–1.72 T and 1.66–1.68 T,respectively.The Ni-doped alloys exhibit better soft-magnetic properties,containing a low coercivity（Hc） of about 5.0 A/m and a high Effective permeability（μe）of（8–10）×10^3,whereas the microalloying of Co leads to a deteriorative Hc of 5.0–13.0 A/m and a μeof（5–8）×10^3.Moreover,microalloying of Ni can increase the ductile-brittle transition（DBT）temperature of the ribbons,while a totally opposite effect is found in the Co-doped alloys.The formation of dense α-Fe（Co,Ni）clusters during annealing process is used to explain the distinct effects of Co and Ni microalloying on the magnetic properties and bending toughness.

Heterostructured crystallization mechanism and its effect on enlarging the processing window of Fe-based nanocrystalline alloys

The harsh melt-spinning and annealing processes of high saturation magnetization nanocrystalline softmagnetic alloys are the biggest obstacles for their industrialization. Here, we proposed a novel strategy to enlarge the processing window by annealing the partially crystallized precursor ribbons via a heterostructured crystallization process. The heterostructured evolution of Fe_(84.75)Si_(2)B_(9)P_(3)_(C0.5)Cu_(0.75)(at.%)alloy ribbons with different spinning rate were studied in detail, to demonstrate the gradient nucleation and grain refinement mechanisms. The nanocrystalline alloys made with industrially acceptable spinning rate of 25-30 m/s and normal annealing process exhibit excellent magnetic properties and fine nanostructure. The small quenched-in crystals/clusters in the free surface of the low spinning rate ribbons will not grow to coarse grains, because of the competitive grain growth and shielding effect of metalloid elements rich interlayer with a high stability. Avoiding the precipitation of quenched-in coarse grains in precursor ribbons is thus a new criterion for the composition and process design, which is more convenient than the former one with respect to the homogenous crystallization mechanism, and enable us to produce high performance nanocrystalline soft-magnetic alloys. This strategy is also suitable for improving the compositional adjustability, impurity tolerance, and enlarging the window of melt temperature,which is an important reference for the future development of composition and process.

Preparation of shape-controlling V0_(2)(M/R)nanoparticles via one-step hydrothermal synthesis

In this study,we developed a facile one-step hydrothermal process that allows to synthesize high-purity V0_(2)(M/R)nanoparticles with various morphologies such as nanorods,nanogranules,nanoblocks,and nanospheres.W dopants are successfully implanted in V02(M/R)unit cells with high doping efficiency,which allows to regulate the size,morphology,and phase of obtained nanoparticles.The underlying regulation mechanism is presented in detail to reveal how hydrothermal products vary with W doping contents,which provides a synthetic strategy for the preparation of shape-controlling V02(M/R)nanoparticles with high purity to satisfy different specific demands for corresponding applications in the field of thermochromic smart windows.