Mo is difficult to sinter densely at a relatively low temperature due to its high melting point. In the present paper,by adding different weight contents of Ni and Cu additives, Mo alloys have been densified at 1473 K...Mo is difficult to sinter densely at a relatively low temperature due to its high melting point. In the present paper,by adding different weight contents of Ni and Cu additives, Mo alloys have been densified at 1473 K for an hour byhot-pressing method, and the optimum contents of Cu and Ni additives have been acquired: when the contents of Niand Cu are 3 and 2 wt pct respectively, the relative density of the sample reaches the maximum value. It was foundthat when the Ni-Cu solid solution was added into Mo alloys. the achieved density is higher than the case of Ni andCu additives. The experimental results indicate that, Ni and Cu play different roles in the process of sintering, theNi-Cu solid solution has the same function as Ni and Cu additives in the course of sintering Mo alloys, It shows moreactivating sintering feature for Mo than the Ni and Cu additives.展开更多
W-Mo composites with different mass fractions of W and Mo were prepared at1473 K by Spark Plasma Sintering technique. The transverse and longitudinal wave velocities of thesamples were accurately measured using the ul...W-Mo composites with different mass fractions of W and Mo were prepared at1473 K by Spark Plasma Sintering technique. The transverse and longitudinal wave velocities of thesamples were accurately measured using the ultrasonic pulse echo overlap method, and the waveimpedance values of the samples were then calculated. The results show that W-Mo system compositesare of nearly full dense and can be regarded as a mechanical mixture system. The ideal mixture modelwas adopted to estimate the wave impedance of W-Mo composites. Comparisons with the experimentaldata demonstrate that the suggested model is sufficiently accurate to predict the wave impedance ofW-Mo composites.展开更多
In contrary to the commonly used arc melting method, samples in the present paper were prepared by the solid state reaction from elemental powders at 1173 K under a flowing Ar atmosphere for 96-168 h. The constituent ...In contrary to the commonly used arc melting method, samples in the present paper were prepared by the solid state reaction from elemental powders at 1173 K under a flowing Ar atmosphere for 96-168 h. The constituent phases and the elemental compositions were determined and shown that the samples were of single phase and stoichiometry. Then the spark plasma sintering technique was used to consolidate them. It is found that, dense ZrNiSn-based compounds with fine grain size and homogeneous microstructure were achieved under the condition of 1123 K/40 MPa/25 min.展开更多
In this study, Cu was added as the third additive to lower the sintering temperature of W-Ni-Fe alloy. By adding 2 wt pct Cu, a dense 93W-3.5Ni-l.5Fe-2.0Cu tungsten alloy was obtained by hot-pressing at a low temperat...In this study, Cu was added as the third additive to lower the sintering temperature of W-Ni-Fe alloy. By adding 2 wt pct Cu, a dense 93W-3.5Ni-l.5Fe-2.0Cu tungsten alloy was obtained by hot-pressing at a low temperature of 1573 K which is a process of liquid-phase sintering. As a result, the morphology of W-Ni-Fe alloy changed obviously after the addition of Cu and the alloy had-higher relative density and rupture strength. The mechanism of the densification of W-Ni-Fe-Cu alloy at the low temperature.was then mainly investigated. It was found that, part sintering activators Ni and Fe could exist in liquid form at 1573 K due to the addition of Cu, which made it easy for Ni and Fe to dissolve W and thus the full densification of W-Ni-Fe-Cu alloy at the low temperature was realized.展开更多
基金This research is sponsored by the National Natural Science Foundation of China under grant No.50171049.
文摘Mo is difficult to sinter densely at a relatively low temperature due to its high melting point. In the present paper,by adding different weight contents of Ni and Cu additives, Mo alloys have been densified at 1473 K for an hour byhot-pressing method, and the optimum contents of Cu and Ni additives have been acquired: when the contents of Niand Cu are 3 and 2 wt pct respectively, the relative density of the sample reaches the maximum value. It was foundthat when the Ni-Cu solid solution was added into Mo alloys. the achieved density is higher than the case of Ni andCu additives. The experimental results indicate that, Ni and Cu play different roles in the process of sintering, theNi-Cu solid solution has the same function as Ni and Cu additives in the course of sintering Mo alloys, It shows moreactivating sintering feature for Mo than the Ni and Cu additives.
基金The research is financially supported by National Natural Science Foundation of China (No. 50171049)China Postdoctoral Science Foundation (No.2003033528)
文摘W-Mo composites with different mass fractions of W and Mo were prepared at1473 K by Spark Plasma Sintering technique. The transverse and longitudinal wave velocities of thesamples were accurately measured using the ultrasonic pulse echo overlap method, and the waveimpedance values of the samples were then calculated. The results show that W-Mo system compositesare of nearly full dense and can be regarded as a mechanical mixture system. The ideal mixture modelwas adopted to estimate the wave impedance of W-Mo composites. Comparisons with the experimentaldata demonstrate that the suggested model is sufficiently accurate to predict the wave impedance ofW-Mo composites.
文摘In contrary to the commonly used arc melting method, samples in the present paper were prepared by the solid state reaction from elemental powders at 1173 K under a flowing Ar atmosphere for 96-168 h. The constituent phases and the elemental compositions were determined and shown that the samples were of single phase and stoichiometry. Then the spark plasma sintering technique was used to consolidate them. It is found that, dense ZrNiSn-based compounds with fine grain size and homogeneous microstructure were achieved under the condition of 1123 K/40 MPa/25 min.
文摘In this study, Cu was added as the third additive to lower the sintering temperature of W-Ni-Fe alloy. By adding 2 wt pct Cu, a dense 93W-3.5Ni-l.5Fe-2.0Cu tungsten alloy was obtained by hot-pressing at a low temperature of 1573 K which is a process of liquid-phase sintering. As a result, the morphology of W-Ni-Fe alloy changed obviously after the addition of Cu and the alloy had-higher relative density and rupture strength. The mechanism of the densification of W-Ni-Fe-Cu alloy at the low temperature.was then mainly investigated. It was found that, part sintering activators Ni and Fe could exist in liquid form at 1573 K due to the addition of Cu, which made it easy for Ni and Fe to dissolve W and thus the full densification of W-Ni-Fe-Cu alloy at the low temperature was realized.
