Nb-Ti-C alloys with different Ti contents(4%-16%,mole fraction)were fabricated by vacuum non-consumable arc-melting method.The results indicate that the alloys contain niobium solid solution(Nb_(ss)),carbides(Nb_(2)C,...Nb-Ti-C alloys with different Ti contents(4%-16%,mole fraction)were fabricated by vacuum non-consumable arc-melting method.The results indicate that the alloys contain niobium solid solution(Nb_(ss)),carbides(Nb_(2)C,(Nb,Ti)C)and eutectic of Nb_(ss)/MC.Carbides in the Nb-Ti-C alloys change from Nb_(2)C to(Nb,Ti)C with the increase of titanium content. Microstructures in the as-cast state include primary plate-like Nb_(2)C,eutectic of Nb_(ss)/Nb_(2)C,Nb_(ss) and secondary needle-like Nb_(2)C in Nb-5Ti-4C alloy,and other microstructures are primary Nb_(ss),eutectic of Nb_(ss)/(Nb,Ti)C.Morphology of carbides are changed apparently through adding different Ti contents,and morphology of Nb_(ss) changes from the cellular structure to dendrite.展开更多
Al-3Ti-1B master alloys were prepared at different processing parameters by the reaction of halide salts,and the grain refining response of Al-7Si alloy was investigated with Al-3Ti-B master alloy.The microstructure o...Al-3Ti-1B master alloys were prepared at different processing parameters by the reaction of halide salts,and the grain refining response of Al-7Si alloy was investigated with Al-3Ti-B master alloy.The microstructure of master alloy and its grain refining effect on Al-7Si alloy were investigated by means of OM,XRD and SEM.Experimental results show that,the size of Al3Ti particles presented in Al-3Ti-1B master alloys increases with the increase of reaction temperature and decreases with the increase of cooling rate.The grain refining efficiency of Al-3Ti-1B master alloy on Al-7Si alloy is mainly attributed to heterogeneous nucleation of Al3Ti particles,and the morphology ofα(Al)changes from coarse dendritic to fine equiaxed.As a result,Al-3Ti-1B master alloy is prepared by permanent mold,and holding at 800 ℃for 30min,which has better grain refining performance on Al-7Si alloy.展开更多
文摘Nb-Ti-C alloys with different Ti contents(4%-16%,mole fraction)were fabricated by vacuum non-consumable arc-melting method.The results indicate that the alloys contain niobium solid solution(Nb_(ss)),carbides(Nb_(2)C,(Nb,Ti)C)and eutectic of Nb_(ss)/MC.Carbides in the Nb-Ti-C alloys change from Nb_(2)C to(Nb,Ti)C with the increase of titanium content. Microstructures in the as-cast state include primary plate-like Nb_(2)C,eutectic of Nb_(ss)/Nb_(2)C,Nb_(ss) and secondary needle-like Nb_(2)C in Nb-5Ti-4C alloy,and other microstructures are primary Nb_(ss),eutectic of Nb_(ss)/(Nb,Ti)C.Morphology of carbides are changed apparently through adding different Ti contents,and morphology of Nb_(ss) changes from the cellular structure to dendrite.
文摘Al-3Ti-1B master alloys were prepared at different processing parameters by the reaction of halide salts,and the grain refining response of Al-7Si alloy was investigated with Al-3Ti-B master alloy.The microstructure of master alloy and its grain refining effect on Al-7Si alloy were investigated by means of OM,XRD and SEM.Experimental results show that,the size of Al3Ti particles presented in Al-3Ti-1B master alloys increases with the increase of reaction temperature and decreases with the increase of cooling rate.The grain refining efficiency of Al-3Ti-1B master alloy on Al-7Si alloy is mainly attributed to heterogeneous nucleation of Al3Ti particles,and the morphology ofα(Al)changes from coarse dendritic to fine equiaxed.As a result,Al-3Ti-1B master alloy is prepared by permanent mold,and holding at 800 ℃for 30min,which has better grain refining performance on Al-7Si alloy.
