The high temperature oxidation behaviors of Ti Cr alloys containing 18% ～ 35% Cr with Laves phase TiCr 2 were investigated at 650 ～ 780?℃ for exposure up to 104?h. The results reveal that chromium content has criti...The high temperature oxidation behaviors of Ti Cr alloys containing 18% ～ 35% Cr with Laves phase TiCr 2 were investigated at 650 ～ 780?℃ for exposure up to 104?h. The results reveal that chromium content has critical significance to the oxidation resistance of the alloys. The scaling rates of the alloys with less than 21% Cr are higher than those measured for pure titanium, but for the alloys with more than 26% Cr their scaling rate is lowered by 1～2 times, under the same oxidizing conditions. Both an external and an internal oxidation layers were observed. The oxidation resistance enhancement by chromium alloying is contributed to the formation of a continuous and compact chromic oxide interleaf in the scale. Oxidation temperature significantly affects the scaling rates of Ti Cr alloys, and the mass gain is doubled with a temperature change from 650?℃ to 700?℃ or from 700?℃ to 780?℃, for the same exposure duration. TiCr 2 shows no negative influence on the high temperature oxidation resistance of the alloys.展开更多
The effect of heat treatment and thermal exposure on the microstructure and mechanical properties of non burning β titanium alloy Ti 25V 15Cr 2Al 0.2C (mass fraction, %) was investigated. It is found that the amount ...The effect of heat treatment and thermal exposure on the microstructure and mechanical properties of non burning β titanium alloy Ti 25V 15Cr 2Al 0.2C (mass fraction, %) was investigated. It is found that the amount of α precipitation in samples after solution treatment followed by air cooling increases with increasing solution temperature. After solution treatment, the alloy was subjected to two different heat treatments to stabilize the material. The results show that the single ageing treatment(700 ℃, 4 h, AC) leads to a large amount of α precipitation, while the triplex treatment(850 ℃, 2 h, FC+700 ℃, 6 h, FC+540 ℃, 6 h, AC) significantly suppresses the formation of α precipitates. It is more important that after long term exposure at 540 ℃(the expected application temperature) samples heat treated by the triplex treatment have markedly higher ductility than those given the single aging treatment. The intermetallic compound TiCr 2 is observed in samples after long term exposure, which further degrades the ductility of the alloy.展开更多
文摘The high temperature oxidation behaviors of Ti Cr alloys containing 18% ～ 35% Cr with Laves phase TiCr 2 were investigated at 650 ～ 780?℃ for exposure up to 104?h. The results reveal that chromium content has critical significance to the oxidation resistance of the alloys. The scaling rates of the alloys with less than 21% Cr are higher than those measured for pure titanium, but for the alloys with more than 26% Cr their scaling rate is lowered by 1～2 times, under the same oxidizing conditions. Both an external and an internal oxidation layers were observed. The oxidation resistance enhancement by chromium alloying is contributed to the formation of a continuous and compact chromic oxide interleaf in the scale. Oxidation temperature significantly affects the scaling rates of Ti Cr alloys, and the mass gain is doubled with a temperature change from 650?℃ to 700?℃ or from 700?℃ to 780?℃, for the same exposure duration. TiCr 2 shows no negative influence on the high temperature oxidation resistance of the alloys.
文摘The effect of heat treatment and thermal exposure on the microstructure and mechanical properties of non burning β titanium alloy Ti 25V 15Cr 2Al 0.2C (mass fraction, %) was investigated. It is found that the amount of α precipitation in samples after solution treatment followed by air cooling increases with increasing solution temperature. After solution treatment, the alloy was subjected to two different heat treatments to stabilize the material. The results show that the single ageing treatment(700 ℃, 4 h, AC) leads to a large amount of α precipitation, while the triplex treatment(850 ℃, 2 h, FC+700 ℃, 6 h, FC+540 ℃, 6 h, AC) significantly suppresses the formation of α precipitates. It is more important that after long term exposure at 540 ℃(the expected application temperature) samples heat treated by the triplex treatment have markedly higher ductility than those given the single aging treatment. The intermetallic compound TiCr 2 is observed in samples after long term exposure, which further degrades the ductility of the alloy.
