95W-3.5Ni-1.5Fe合金高温性能、组织及断裂机制

研究了95W-3.5Ni-1.5Fe合金在400～1100℃范围内的高温拉伸力学性能及其断口特征,并分析了其断裂机制.结果表明:合金的抗拉强度及屈服强度均随温度升高而降低,延伸率和断面收缩率随温度升高呈现先增加后降低的关系,600℃时延伸率和断面收缩率达到最大值.对其断口分析结果表明:在400～600℃范围内,由于钨相发生了塑脆转变,钨颗粒塑性提高使得两相协调变形能力增强,合金塑性提高.而当温度升高到700℃以上,粘结相发生动态再结晶软化,钨相和粘结相界面结合强度大幅度下降,外加应力不能由粘接相传递到钨颗粒,其两相协调变形能力变差,导致合金强韧性急剧下降.

Mechanical Properties, Microstructure and Fracture Mechanism of 95W-3.5Ni-1.5Fe Alloys at High Temperature

The mechanical properties and fracture characteristics of 95W-3.5Ni-1.5Fe alloys were investigated by tension in the temperature range of 400-1100 oC and the fracture mechanism was analyzed. The results show that the ultimate tensile strength (UTS) and the yield strength of the alloy decrease with the increasing temperature, while the elongation and the reduction of fracture surface area firstly increase up to the maximum value at 600 oC and then decrease with the increasing temperature. The improved ductility of the alloys in the temperature range of 400-600 oC is due to the enhanced comparable deformation capacity between tungsten and the matrix phases by ductile-brittle transformation of tungsten phase. Above 700 oC, dynamic recrystallization occurs in the matrix, which deteriorates the strength of tungsten/matrix interfaces. Hence, the applied stress can not be transited from the matrix to tungsten particles and the comparable deformation capacity of tungsten and matrix is reduced, resulting in a sharp decrease in strength and toughness of alloys.