W-Fe-C复合材料的低温致密化机制及力学性能

Low-Temperature Densification Mechanism and Mechanical Properties of W-Fe-C Composites

摘要:

采用放电等离子烧结在不同烧结温度下制备W-Fe-C复合材料，对其烧结行为、物相组成、微观形貌以及力学行为进行表征，并分析其致密化机理。结果表明，随温度升高，复合材料中增强相由Fe₆W₆C转变为Fe₃W₃C，最终变为Fe₂W₂C。1400 ℃烧结后，样品相对密度高达99.2%，极限抗压缩强度为2455.15 MPa，变形率为25.42%。W-Fe-C复合材料在保温阶段存在一个特殊的蠕变恢复阶段，此阶段致密化速率几乎为零。W-Fe-C复合材料有效应力指数（）值约为1和2时，活化能分别为341.27和1005.73 kJ/mol，高于纯W，但由于原位反应促进扩散，其相对密度高于纯W。本研究为低温制备钨基复合材料提供了新思路。

Abstract:

The W-Fe-C composites were prepared using spark plasma sintering at various sintering temperatures, and their sintering behavior, phases, microstructure, and mechanical properties were characterized. The densification mechanism was also analyzed. The results show that as the temperature increases, the reinforcement phase in the composite transitions from Fe₆W₆C to Fe₃W₃C, and finally to Fe₂W₂C. After sintering at 1400 ℃, the sample achieves a relative density of 99.2%, with an ultimate compressive strength of 2455.15 MPa and a deformation rate of 25.42%. During the holding stage, the W-Fe-C composite exhibits a unique creep recovery stage, where the densification rate is nearly zero. When the effective stress exponent (n) is approximately 1 and 2, the estimated activation energies are 341.27 and 1005.73 kJ/mol, respectively, which are higher than those of pure tungsten. However, because the in-situ reaction promotes diffusion, the relative density of the W-Fe-C composites exceeds that of pure tungsten. This study provides a new approach for the low-temperature fabrication of tungsten-based composites.