Ni-Fe alloy nanoparticles were able to be prepared by a one-step hydrazine reduction, where the formation mechanism is unclear. In this paper, Ni_1xFe_x nanoparticles with a composition gradient were prepared, and the change in composition gradient in the Ni_1 − xFe_x nanoparticles was found to be affected by Fe content. Furthermore, it was surprising that the increase in Fe content significantly increased the formation rate of Ni_1 − xFe_x nanoparticles, which was difficult to explain via thermodynamics. By further analyzing the element distribution and microstructure of the intermediate products of the Ni_1 − xFe_x nanoparticles, a formation mechanism was proposed for the Ni_1 − xFe_x nanoparticles. In this formation mechanism, Ni_1 − xFe_x(OH)₂ was confirmed as the reduced intermediate, and the composition distribution of the Ni_1 − xFe_x nanoparticles was primarily controlled by reaction kinetics. Finally, the existence of the composition gradient in the Ni_1 − xFe_x nanoparticles had a great effect on their coercivity, due to the change in internal stress. This work provides a reference for preparation and a performance study of alloy nanoparticles with a composition gradient.

Ni-Fe合金纳米粒子能够通过一步肼还原法制备，其中形成机理尚不清楚。在本文中，镍_{1 X}的Fe _X纳米粒子组成梯度制备，并在镍中的组分梯度的变化_{1 -  X}的Fe _X被发现纳米颗粒由Fe的含量的影响。此外，令人惊讶的是，Fe含量的增加显着增加了Ni _{1-  x} Fe _x纳米颗粒的形成速率，这很难通过热力学来解释。通过进一步分析Ni _{1-  x}中间产物的元素分布和微观结构Fe _x纳米粒子，提出了Ni _{1-  x} Fe _x纳米粒子的形成机理。在该形成机理中，证实Ni _{1-  x} Fe _x（OH）₂为还原的中间体，并且主要通过反应动力学控制Ni _{1-  x} Fe _x纳米颗粒的组成分布。最后，Ni _{1-  x} Fe _x中存在成分梯度由于内部应力的变化，纳米颗粒对其矫顽力有很大影响。这项工作为具有组成梯度的合金纳米粒子的制备和性能研究提供了参考。