Abstract Elongated β–Si 3 N 4 crystals have a significant influence on the mechanical property of Fe–Si 3 N 4 composite. In this paper, the formation mechanism of elongated β–Si 3 N 4 crystals in Fe–Si 3 N 4 composite was investigated. During the preparation process, β–Si 3 N 4 crystals developed in a spiral and layer growth mechanism in the dense areas. They kept growing from the dense areas and formed radially distributed elongated crystals with hexagonal prismatic morphology as time went on. As for the formation mechanism, the (100) crystal plane of β–Si 3 N 4 from Si-N-O melt is mainly the vicinal crystal planes growth with different angles from the (100) crystal plane. At the later stage, the crystallization and the diffusion forces in Si-N-O molten phase decreased. However, the short range diffusion remained active and resulted in the gradient distribution of N content near the boundary. With the temperature decreasing, the disappearance of the short range diffusion implied the end of the crystallization process of the elongated β–Si 3 N 4 crystals.

中文翻译：

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Fe-Si 3 N 4 复合材料中细长β-Si 3 N 4 晶体的闪燃形成机制

摘要 细长的β-Si 3 N 4 晶体对Fe-Si 3 N 4 复合材料的力学性能有显着影响。本文研究了Fe-Si 3 N 4 复合材料中细长β-Si 3 N 4 晶体的形成机制。在制备过程中，β-Si 3 N 4 晶体在致密区域以螺旋和层状生长机制发展。随着时间的推移，它们从密集区域不断生长，并形成放射状分布的细长晶体，具有六边形棱柱形形态。至于形成机制，来自Si-NO熔体的β-Si 3 N 4 的（100）晶面主要是与（100）晶面成不同角度的邻晶面生长。在后期，Si-NO 熔相中的结晶和扩散力降低。然而，短程扩散保持活跃，并导致边界附近 N 含量的梯度分布。随着温度的降低，短程扩散的消失意味着拉长的β-Si 3 N 4 晶体的结晶过程结束。