Sintering time and atmosphere influences on the microstructure and mechanical properties of tungsten heavy alloys
Sintering time and atmosphere influences on the microstructure and mechanical properties of tungsten heavy alloys
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DOI：
10.1007/bf02660866
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发表时间：
1992
期刊：
影响因子：
--
通讯作者：
R. German;A. Bose;S. Mani
中科院分区：
文献类型：
--
作者：
R. German;A. Bose;S. Mani
高密度钨合金的力学性能对加工周期很敏感，并受到残余气孔率的不利影响。烧结时间超过2小时通常会导致气孔生长，性能下降。优化的烧结气氛的发展使人们能够探索更长的烧结时间，而不会因为气孔生长而导致性能显著下降。最佳的烧结周期是在1480℃下烧结两种重合金成分(88%和95%W)，时间长达600分钟。88%W样品坍塌，但95%W样品完全致密，适合拉伸测试。在较长的烧结时间下，钨颗粒变平，钨的连续性降低，表明固液界面向低能组态转变。立方平均晶粒度随等温烧结时间呈线性变化。这使得可以确定颗粒尺寸对机械性能的影响，显示出屈服强度随着时间的增加而下降，这与Hall-Petch行为一致。当烧结时间在30-90分钟时，抗拉强度和延伸率最高，反映出残余气孔率最小。
The mechanical properties of tungsten heavy alloys are sensitive to the processing cycle and are adversely affected by residual porosity. Sintering times greater than 2 hours usually result in pore growth with degraded properties. The development of an optimized sintering atmosphere has allowed exploration of long sintering times without significant property degradation due to pore growth. The optimal cycle was used to sinter two heavy alloy compositions (88 and 95 wt pct W) for times up to 600 minutes at 1480 °C. The 88 pct W samples slumped, but the 95 pct W samples were fully densified and suitable for tensile testing. At long sintering times, the tungsten grains flattened and the tungsten contiguity decreased, indicating a transition to low-energy configurations for the solid-liquid interfaces. The cube of the mean grain size varied linearly with the isothermal sintering time. This allowed determination of grain size effects on mechanical properties, showing a decreasing yield strength with increasing time in agreement with the Hall-Petch behavior. The tensile strength and elongation were highest for sintering times from 30 to 90 minutes, reflecting a minimum in the residual porosity.