A new model was established to calculate the real vapor pressure of the Al element in the molten Ti x Al ( x = 25 ～ 50, mole fraction, %) alloy. The effects of the holding time, chamber pressure, mole fraction of Al ...A new model was established to calculate the real vapor pressure of the Al element in the molten Ti x Al ( x = 25 ～ 50, mole fraction, %) alloy. The effects of the holding time, chamber pressure, mole fraction of Al and melting temperature on the real vapor pressure of Al element in the vacuum chamber were analyzed. Because of the impeding effect of the real vapor pressure on the evaporation loss rate, within a short time (less than 10?s), the real vapor pressure tends to a constant value. When the chamber pressure is less than the saturated vapor pressure of the Al component, the real vapor pressure of Al is equal to the chamber pressure. While when the chamber pressure is larger than the saturated vapor pressure, the real vapor pressure is equal to the saturated vapor pressure of the Al element of the same condition.展开更多
铸造耐热Al-Si-Cu-Ni-Mg合金是制备高功率密度发动机活塞等耐热轻量化部件的重要基础材料,通过添加高熔点、低热扩散系数的Sc元素来调控合金的相结构和形貌是提升此类合金耐温性的重要思路。因此,探究了Sc元素添加及其含量对铸造耐热Al-...铸造耐热Al-Si-Cu-Ni-Mg合金是制备高功率密度发动机活塞等耐热轻量化部件的重要基础材料,通过添加高熔点、低热扩散系数的Sc元素来调控合金的相结构和形貌是提升此类合金耐温性的重要思路。因此,探究了Sc元素添加及其含量对铸造耐热Al-Si-Cu-Ni-Mg活塞合金凝固组织和热暴露过程中富铜镍相组织演变的影响。结果表明,随Sc含量增加,活塞合金中形成Al Si CuNiSc新相,并且Al Si CuNiSc相的数量和尺寸随Sc含量的增加而增加;此外,随着Al Si CuNiSc相的形成,δ-Al_(3)CuNi相发生由典型共晶层片向棒杆状组织的转变。热暴露过程中,δ-Al_(3)CuNi相中的Cu和Ni原子向α-Al基体中扩散,并在δ-Al_(3)CuNi的相界面处形成纳米尺度的γ-Al_(7)Cu_(4)Ni相;而富Sc的Al Si CuNiSc相在热暴露前后形貌和成分几乎不发生变化,表现出极高的热稳定性;分析认为,高熔点、低热扩散系数的Si和Sc等原子在富铜镍相中的存在极大提高了富铜镍相的热稳定性。展开更多
文摘A new model was established to calculate the real vapor pressure of the Al element in the molten Ti x Al ( x = 25 ～ 50, mole fraction, %) alloy. The effects of the holding time, chamber pressure, mole fraction of Al and melting temperature on the real vapor pressure of Al element in the vacuum chamber were analyzed. Because of the impeding effect of the real vapor pressure on the evaporation loss rate, within a short time (less than 10?s), the real vapor pressure tends to a constant value. When the chamber pressure is less than the saturated vapor pressure of the Al component, the real vapor pressure of Al is equal to the chamber pressure. While when the chamber pressure is larger than the saturated vapor pressure, the real vapor pressure is equal to the saturated vapor pressure of the Al element of the same condition.
文摘铸造耐热Al-Si-Cu-Ni-Mg合金是制备高功率密度发动机活塞等耐热轻量化部件的重要基础材料,通过添加高熔点、低热扩散系数的Sc元素来调控合金的相结构和形貌是提升此类合金耐温性的重要思路。因此,探究了Sc元素添加及其含量对铸造耐热Al-Si-Cu-Ni-Mg活塞合金凝固组织和热暴露过程中富铜镍相组织演变的影响。结果表明,随Sc含量增加,活塞合金中形成Al Si CuNiSc新相,并且Al Si CuNiSc相的数量和尺寸随Sc含量的增加而增加;此外,随着Al Si CuNiSc相的形成,δ-Al_(3)CuNi相发生由典型共晶层片向棒杆状组织的转变。热暴露过程中,δ-Al_(3)CuNi相中的Cu和Ni原子向α-Al基体中扩散,并在δ-Al_(3)CuNi的相界面处形成纳米尺度的γ-Al_(7)Cu_(4)Ni相;而富Sc的Al Si CuNiSc相在热暴露前后形貌和成分几乎不发生变化,表现出极高的热稳定性;分析认为,高熔点、低热扩散系数的Si和Sc等原子在富铜镍相中的存在极大提高了富铜镍相的热稳定性。
