Abstract
Fine-grained W-6Ni-4Mn alloys were fabricated by spark plasma sintering (SPS) using mechanical milling W, Ni and Mn composite powders. The relative density of W-6Ni-4Mn alloy increases from 71.56% to 99.60% when it is sintered at a low temperature range of 1000–1200 °C for 3 min. The spark plasma sintering process of the alloy can be divided into three stages, which clarify the densification process of powder compacts. As the sintering temperature increases, the average W grain size increases but remains at less than 7 µm and the distribution of the binding phase is uniform. Transmission electron microscopy (TEM) observation reveals that the W-6Ni-4Mn alloy consists of the tungsten phase and the γ-(Ni, Mn, W) binding phase. As the sintering temperature increases, the Rockwell hardness and bending strength of alloys initially increases and then decreases. The optimum comprehensive hardness and bending strength of the alloy are obtained at 1150 °C. The main fracture mode of the alloys is W/W interface fracture.
Highlights
The kinetic energy penetrators mainly include depleted uranium alloys (DU) and tungsten heavy alloys (WHAs) [1]
As sintering phase sintering; most of them were combined together, leading to larger W grain size, and we found increases, the liquid-phase sintering stage begins, the γ-(Ni, Mn) binding phase is formed, and small that the surface of the sintered alloy has a lot of micropores (Figure 4a,b)
The W-6Ni-4Mn alloys with a high densification of 99.6% are fabricated by spark plasma sintering (SPS) at 1150 ◦ C for min
Summary
The kinetic energy penetrators mainly include depleted uranium alloys (DU) and tungsten heavy alloys (WHAs) [1]. In order to overcome the defects of traditional liquid sintering, the SPS technique has been successfully used to prepare WHAs [14,15]. SPS is a newly arisen sintering technique, during the sintering process, a high densification rate is favored whereas coarsening induced by surface diffusion is minimized, and grain growth can be suppressed [14]. In previous study [13], we found that the densification temperature of spark plasma sintered W-Ni-Mn alloy by simple mixing starting powders was as high as 1250 ◦ C. For fabricating high-density W-Ni-Mn alloy with finer W grain at low temperature, mechanical milling (MM) was applied to the pretreatment of starting powders in this study, and the densification behavior of the alloys has been discussed especially by the sintering curve. Microstructure and mechanical properties of the alloys were investigated
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