Low-expansion alloys are of great importance and can be used for the development of new aerospace materials. Herein, we report diverse rare earth quasicrystal alloys fabricated by the vacuum suction casting process. The effects of the addition of cerium (Ce) on the microstructure, thermal expansion properties and microhardness of the Al-Cu-Fe alloy were systematically investigated. This study discovered the tiny Al-Cu-Fe-Ce microstructure. A uniform distribution could be achieved after Ce addition amount is elevated. At the Ce addition amount of 1 at%, the lowest alloy thermal expansion coefficient was obtained. The alloy exhibited the maximum microhardness under these conditions. The microhardness of alloys containing 1 at% of Ce was approximately 2.4 times higher than the microhardness exhibited by alloys devoid of Ce additives. The coefficient of thermal expansion decreases by approximately 20%. The use of the suction casting process and the addition of an appropriate amount of Ce can potentially help design and develop Al-Cu-Fe-Ce alloys.
In this paper, the bottom pouring vacuum suction casting is used, and the TiAl-based alloy blade with good face quality was obtained. Bottom pouring vacuum suction casting obtained Ti-47Al-5Nb-0.5Si alloy fine structure, the average grain size is 20um or less. Metal permanent forced cooling effect increases the undercooling degree, and the formation of Ti5Si3 can hinder the grain growth and the formation of nucleation particles, and Nb elements are conducive to the formation of B2 phase, and these three reasons refined the grain size.
Rapid solidification of Co-Si alloys was investigated by using vacuum suction casting in this study. Different microstructures and intermediate phases were obtained. Eutectic εCo phase and eutectoid εCo + αCo2Si structures were obtained in the first eutectic Co76.9Si23.1 alloy. The microstructures of hypereutectic Co70Si30 alloys were composed of primary αCo2Si phase and interdendritic lamellar eutectoid εCo + αCo2Si. While for hypoeutectic Co63Si37 alloy at the second eutectic point, CoSi dendrites were the primary phase, and αCo2Si+CoSi eutectoid structures can be seen at the interdendritic region. Especially, a metastable CoSi2 phase was found in Co63Si37 alloy. This indicates that eutectoid decomposition βCo2Si→ CoSi+αCo2Si is restrained in eutectic Co60.3Si39.7 alloy. For rapid solidified Co55Si45 and Co52Si48 alloys, αCo2Si+CoSi eutectoid structures were not observed, while metastable CoSi2 were obtained. The higher hardness achieved in Co-Si alloys at the second eutectic point, for the reason of the higher volume fractions of compound phases.
Influence of cerium content on the microstructure and thermal expansion properties of suction cast Al-Cu-Fe alloys
