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在考虑真实粉末压块的液相烧结机制时,应研究液相的流动和分布。为观察Fe-Cu合金液相烧结时的孔封闭过程,用以粗Cu球形粉末(150～160μm)与铁粉(2～4μm或36～53μm)相混合制得的压块获得人为的大球形孔。进行了三组实验以观察成分、预烧结制度、铁粉颗粒大小,压制压力,烧结时间和热压的作用。在液相烧结时,隔离孔通过充填液相封闭与收缩过程一起进行。它随着铁粉颗粒减小,预烧结温度降低、铜含量提高、压制压力降低和烧结时间增长而发展。对于以9t/cm~2压制的试样,在液相出现后即发生膨胀,随后缓慢收缩,坚实骨架的形成和加热时孔内气体压力的增加阻碍孔的封闭过程。在热压作用下的试样,富铁基体与液相一道流入隔离孔,这归因于热压时起支配作用的致密化机制——塑性流动。
When considering the liquid-phase sintering mechanism of a real powder compact, the flow and distribution of the liquid phase should be studied. In order to observe the pore-sealing process during the liquid-phase sintering of Fe-Cu alloy, an artificial large spherical shape was obtained by using a compact obtained by mixing coarse Cu spherical powder (150-160 μm) with iron powder (2-4 μm or 36-53 μm) hole. Three sets of experiments were conducted to observe the effect of the composition, the pre-sintering system, the size of the iron particles, the pressing pressure, the sintering time and the hot pressing. During liquid phase sintering, the isolation holes are closed and filled by the liquid phase. It develops as iron powder particles decrease, presintering temperature decreases, copper content increases, compression pressure decreases, and sintering time increases. For the sample pressed at 9t / cm ~ 2, the liquid expands after the liquid phase appears, and then slowly shrinks. The formation of a solid skeleton and the increase of gas pressure in the pores during heating impede the pore sealing process. Under hot pressing, the iron-rich matrix flows into the isolation hole together with the liquid phase due to the densification mechanism - ductile flow, which dominates the hot pressing.