液Zn对Fe_2Al_5涂层侵蚀的相变过程研究

Erosion phase transition of Fe_2 Al_5 coating in molten zinc

本文对Fe2Al5涂层在液态Zn中的侵蚀相变过程进行了研究,实验结果表明:在侵蚀初期,靠界面张力平衡的作用,先发生热侵蚀,在试样表面形成热蚀沟,当热蚀沟达到一定程度后,液Zn与Fe2Al5相由不浸润变为浸润;同时Zn原子扩散进入Fe2Al5相并形成Fe2Al5-Znx固溶体相(η相);随着侵蚀时间的增加,发生在腐蚀界面上的液Zn对Fe2Al5涂层的侵蚀过程是恒温相变过程,相变过程使Fe2Al5涂层发生定向熔化.相变的驱动力来自于相成分的改变所引起的各相自由能的变化及各相间的相平衡的重新建立.

The mechanism of erosion phase transition of Fe2Al5 coating in molten zinc was investigated.Experimental results indicated that etched grooves caused by interfacial tension equilibrium driving formed on sample surface.The Fe2Al5 phase,on where zinc did not adhere at the early stage of erosion,was infiltrated by zinc and solid solution Fe2Al5-Znx（η phase） was formed due to zinc atoms diffusing into Fe2Al5phase.The erosion process of Fe2Al5 in molten zinc is directed melt at the interface caused by phase transition to drive.There were three types of phase interface,η/L,η/（η＋δ）/L and η/（η＋δ）/δ＋L,formed in corroded area.The solid（S）/liquid（L） interface was phase-equilibrium interface and the S/S interface like η/（η＋δ） and（η＋δ）/δ were non phase-equilibrium interfaces at erosion temperature.The demand of phase-equilibrium interfaces and phase transitions of non-equilibrium interfaces,η→（η＋δ） and（η＋δ）→δ,made the S/L interface move towards to solid phase and Fe2Al5 phase was corroded by molten zinc.