弥散强化钨镍铁高比重合金的制备及性能研究

Preparation and Properties of Dispersion Strengthening W-Ni-Fe Heavy Alloy

钨基高比重合金在航天航空、兵器等行业中有着广泛应用,但传统钨镍铁高比重合金需通过后续形变强化处理提高力学性能,限制了其在国防工业和民用领域的广泛应用。利用弥散强化手段,当强化相在基体内呈弥散质点或粒状分布时,可显著提高合金强度和硬度,且塑性和韧性下降不大。本文研究了Y_2O_3弥散强化95W-3.5Ni-1.5Fe合金的制备工艺及性能。与传统钨镍铁高比重合金制备相比,本文首先利用化学气相迁移机制制备Y_2O_3分布在颗粒内部的弥散强化钨粉,重点研究原料种类对弥散强化钨粉粒度的影响以及成形、烧结工艺,利用X射线衍射(XRD)分析、场发射扫描电子显微镜(FESEM)对弥散强化钨粉及弥散强化钨进行性能表征。结果表明:WO2.9+Y_2O_3体系制备的弥散强化钨粉粒度最小,约1μm;经1480℃烧结90 min,弥散强化钨镍铁高比重合金的相对密度达98.6%,Y_2O_3在钨晶粒内呈弥散分布;钨合金的显微硬度达HV 532,表现出较高韧性。

Tungsten heavy alloys were widely used in the realms such as aerospace and ordnance industries. However, the afterward deformation enhancement process which was imperative for traditional tungsten heavy alloy fabrication restrained its further applications in the military and civil industries. Comparatively, using the dispersed strengthening phase such as the dispersoid particles in the ma- trix, the strength and hardness of the heavy alloy could be noticeably improved and meanwhile the loss of plasticity and toughness re- mained insignificant via the dispersion strengthening method. The preparation and properties of Y2O3 dispersion strengthening 95W- 3.5Ni-1.5Fe alloy were studied in this work. Different from the traditional methods for preparing the dispersion strengthening alloys, the Y2O3 dispersion strengthening tungsten powder was fabricated via chemical vapor transport at first. The influences of raw materials on the particle size of dispersion strengthening tungsten powder were studied. The pressing and sintering process were optimized. The properties of tungsten powder and dispersion strength tungsten were investigated by X-ray diffraction （XRD） and field emission scanning electron microscopy （FESEM）. The results showed that the dispersion strengthening tungsten powder prepared from WO2.9 and Y2O3 had the minimum size （about 1 μm）. After sintering at 1480 ℃ for 90 min, the relative density of the Y2O3 dispersion strengthening tungsten alloy achieved 98.6%, and the Y2O3 was well-dispersed in the tungsten grains. The microhardness was HV 532 and dispersion strengthening tungsten heavy alloy showed good toughness.