By means of rapid solidification, two Al<sub>65</sub>Cu<sub>20</sub>Fe<sub>15</sub> powders were prepared with water and liquid N<sub>2</sub> as the respective cooling a...By means of rapid solidification, two Al<sub>65</sub>Cu<sub>20</sub>Fe<sub>15</sub> powders were prepared with water and liquid N<sub>2</sub> as the respective cooling agent. Both powders are composed of a qnasicrystalline icosahedral phase and a crystalline hexagonal phase, with the water-cooled alloy having a higher crystalline phase content. In the isothermal an nealing process, the crystalline phase in the water-quenched alloy begins to decrease at 500℃ and then disap pears at 600～700℃. At about 800℃, new crystalline phases form, and at 900℃, the quasicrystalline phase disappears. Conversely, in the liquid N<sub>2</sub> quenched alloy, the quasicrystalline phase starts to decrease at about 500℃. and the hexagonal phase decomposes into new crystalline phases. At 700～800℃, the quasicrystalline phase disappears. For the water-cooled sample, the quenching at 100～200C makes the crystalline to quasicrystalline phase transformation start at a lower temperature and the crystallization of the quasicrystal occur at a higher temperature. For the liquid N<sub>2</sub> quenched alloy, the quenching at 100～400℃, did not affect its phase transformation at high temperature.展开更多
文摘By means of rapid solidification, two Al<sub>65</sub>Cu<sub>20</sub>Fe<sub>15</sub> powders were prepared with water and liquid N<sub>2</sub> as the respective cooling agent. Both powders are composed of a qnasicrystalline icosahedral phase and a crystalline hexagonal phase, with the water-cooled alloy having a higher crystalline phase content. In the isothermal an nealing process, the crystalline phase in the water-quenched alloy begins to decrease at 500℃ and then disap pears at 600～700℃. At about 800℃, new crystalline phases form, and at 900℃, the quasicrystalline phase disappears. Conversely, in the liquid N<sub>2</sub> quenched alloy, the quasicrystalline phase starts to decrease at about 500℃. and the hexagonal phase decomposes into new crystalline phases. At 700～800℃, the quasicrystalline phase disappears. For the water-cooled sample, the quenching at 100～200C makes the crystalline to quasicrystalline phase transformation start at a lower temperature and the crystallization of the quasicrystal occur at a higher temperature. For the liquid N<sub>2</sub> quenched alloy, the quenching at 100～400℃, did not affect its phase transformation at high temperature.
