Hydrogen,as a temporary element in titanium alloys,is very good in controlling microstructure.The microstructure and phase transformation of Ti6A14V alloy are affected by the amount of TiH,added into the melt of Ti6A14V alloy during the induction skull melting（ISM） process.This process,called melt hydrogenation,was studied in this paper through the use of optical microscopy,scanning electron microscopy（SEM） and transmission electron microscopy（TEM）.The results are as follows:after melt hydrogenation,both the solidification macrostructure and microstructure of Ti6A14Valloy are refined;theαphase precipitates in a lamellar form with the residualβphase from the grain boundaries;δ-hydrides precipitate during the solidification process as a result of the existence of hydrogen.The S phase with an F.C.C.structure can be observed by TEM in theαphase laminae of specimens with 1.25%TiH2.In addition,the dependence of the microhardness of specimens on the weight percentage of TiH,added to the melt during the ISM process was also studied.
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