K titanium contot,caleulated by Nmay i rory high,aithough cannot calculate the value accurately as the shortage of suifable thermodynamic data.When the overall system does nct reach the thermedynamic equilibrium, the pure TiN powder will decompese in the liquid metal. The equilibrium nitrogen content for reaction (2)decreases with decreasing the temperature of the alloy system,some new type nitride inclusions,concerning with the composition of the alloy melted,will precipitate from solution during the solidification process.As the liquid metal,in which the pure TiN powder was added,only remained in the crucible for 2 minites,the nitrogen distribution might be heterogeneous in the melt.At the place where the TiN powder just decomposed,the nitrogen content might be higher,consequently,the inclusicn cluster mentioned above intended to form. 2 The Behavior of inclusion during the VAR and ESR Processes of Superalloys The type of inclusions in the high Al,Ti alloy GH220 (311220),high Ti low Al alloy GH132,without Al,Ti alloy GH36 and the hot alloy GH169 has been studied by using optical microscope and scanning electron microscope.It was found that the main inclusions in the alloys tested are MC type inclusions inclu- ding primary carbides and nitride type inclusions.Usually,the former contains some degree of nitrogen and the latter is titanium nitride with some carbon solution (for GH132,GH220)or titanium,niobium nitride with some carbon solution (for GH169).It is to be noted that the alloy GH36 contains 700-1000 ppm nitrogen,but the main inclasions are MC type carbides containing V,Nb,C and N,no nitrides have been found in it (see Table 3). As the pure TiN powder can rapidly decompose in the liquid GH169 and GH132 at 1550C,the inclusions (carbides and nitrides)in the GH169,GH220, GH132 and GH36 should be able to decompose during the VAR and ESR pro- cesses. Table 3.The Composition of Inclusions in the ESR Ingot of GH36(3M481),wt% Inclusion Nb Cr Mo Fe Ni Mn Si 1 60.77.15.51.420.5 2.23.10.1 2 26.645.56.33.15.40.51.0 0.0 If the inclusions in the superalloys decompose during ihe VAR and ESR pro- 505几 ， 〔 〕 一 了荞万 一 ， 一 。 · ， ，， · ， 从 、 厂 飞 一 丫 五 互。 上 ， 了 五 从 五 、 、 ， · 几 叭 了 ， 手 厂 ， 手 ， 从 · ， 。 ， 从 、 ， 。 ， 玉 ， ， 。 如、 ， ， ， ， 一 一 ， ， ， 一 一 ， ， ， ， 住 ， ， ， ， 一 上 日土，﹄ 。 。 。 。 。 。 。 。 。 。 。 。 。 扭