TC4钛合金离子渗氮层的微观结构和性能

Microstructure and Property of Ion Nitrided Layer in TC4 Titanium Alloy

钛合金的表面硬度较低,耐磨性较差,但通过渗氮等表面处理可提高其表面硬度从而改善耐磨性。对TC4钛合金分别在850℃、900℃和950℃离子渗氮5h。检测了渗氮层的显微组织、厚度、表面硬度和硬度分布及耐蚀性能。结果表明:不同温度离子渗氮的TC4合金渗层主要由TiN、Ti2 N相组成;随着渗氮温度的升高,渗层增厚,950℃离子渗氮的合金化合物层厚度为12μm,扩散层厚度为100μm;经离子渗氮的TC4合金能耐氯离子的侵蚀,其自腐蚀电位提高,耐蚀性提高;850℃离子渗氮的TC4合金耐蚀性最佳,这可能与TiN相更多和渗层更致密有关。

Titanium alloys have lower hardness and therefore poor wear resistance,however,may exhibit higher surface hardness thereby better wear resistance after surface treating such as nitriding.TC4 titanium alloy was ion nitrided at 850,900 and 950℃ for 5 h,respectively.The ion nitrided layers were tested for microstructure,thickness,surface hardness,hardness distribution,and corrosion resistance.The results indicated that(a) the cases of the TC4 alloy ion nitrided at different temperatures were mainly composed of TiN and Ti;N phases;(b) as the ion nitriding temperature increased,the case became thicker,and the compound layer of the alloy ion nitrided at 950℃ was as thick as 12 μm,and its diffusion layer was as thick as 100 μm;(c) the TC4 alloy ion nitrided survived attack of chlorion,had higher self-corrosion potential thereby better corrosion resistance;and(d) the TC4 alloy ion nitrided at 850℃ given the best corrosion resistance,which is likely to relate to even more TiN phase and even denser case.