A promising method of improving the densification of powder metallurgical steel components is to blend nanopowder with the otherwise typically used micrometre-sized powder. The higher surface-to-volume ratio of nanopowder is hypothesized to accelerate the sintering process and increase the inter-particle contact area between the powder particles. This is supposed to enhance the material transport and improve the densification. In the present investigation, water-atomized iron powder (− 45 μm) was mixed separately with pure iron and low-carbon steel nanopowder, each at a ratio of 95 to 5 pct. These powder mixes were compacted at different pressures (400, 600 and 800 MPa) and then sintered at 1350 °C in a pure hydrogen atmosphere. The sintering behavior of the powder blend compacts was compared to that of the compact with micrometre-sized powder only. Densification commenced at much lower temperatures in the presence of nanopowder. To understand this, sintering at intermittent temperatures such as 500 °C and 700 °C was conducted. The fracture surface revealed that the nanopowder was sintered at between 500 °C and 700 °C, which in turn contributed to the densification of the powder mix at the lower temperature range. Based on the sintering experiments, an attempt was made to calculate the activation energy and identify the associated sinter mechanism using two different approaches. It was shown that the first approach yielded values in agreement with the grain-boundary diffusion mechanism. As the nanopowder content increased, there was an increase in linear shrinkage during sintering.

一种改善粉末冶金钢部件致密化的有前途的方法是将纳米粉末与原本通常使用的微米级粉末混合。据推测，纳米粉末具有较高的表面积体积比，以加速烧结过程并增加粉末颗粒之间的颗粒间接触面积。据认为这可以增强材料的输送并改善致密性。在本研究中，水雾化铁粉（-45μm）分别与纯铁和低碳钢纳米粉以95至5 pct的比例混合。将这些粉末混合物在不同的压力（400、600和800 MPa）下压实，然后在1350°C的纯氢气氛围中烧结。将粉末混合物压块的烧结行为与仅具有微米级粉末的压块的烧结行为进行了比较。在存在纳米粉的情况下，致密化在更低的温度下开始。为了理解这一点，在诸如500℃和700℃的间歇温度下进行烧结。断裂表面表明，纳米粉末是在500°C和700°C之间烧结的，这又有助于在较低温度范围内粉末混合物的致密化。根据烧结实验，尝试使用两种不同的方法来计算活化能并确定相关的烧结机理。结果表明，第一种方法产生的值与晶界扩散机制一致。随着纳米粉末含量的增加，烧结过程中线性收缩率增加。