高温铝熔液在旋转多孔介质内的渗透与瞬态固化和再熔过程

针对离心渗铸板材工艺中金属铝熔液在旋转的Al₂O₃预型体内的充型过程,考虑离心惯性力对金属铝熔液的瞬态固化与再熔过程的影响,研究了伴随有瞬态固化和再熔现象的流场温度分布以及熔融区长度和固化率瞬态变化规律,推导了渗透界面和再熔界面移动速度计算公式,建立了界面速度与温度的耦合关系。结果表明:当Al₂O₃颗粒预热温度低于铝熔化温度时,渗透过程出现了瞬态固化和再熔现象,液固共熔区随渗透过程不断向前推进,共熔区长度和固化率随渗透过程而增长。随着孔隙率和转速的减小,共熔区内固化率提高,渗透前沿和再熔前沿界面移动速度减小。但孔隙率的减小使两种界面移动速度差值增大,液固共熔区长度增长;而转速的减小使两种界面移动速度差值缩小,液固共熔区长度缩短。

INFILTRATION AND SOLIDIFICATION/REMELTING OF MOLTEN ALUMINUM IN A CENTRIFUGAL FORCE FIELD

The adiabatic infiltration and the solidification/remelting of molten aluminum through a porous preform in a centrifugal force field are modeled numerically. The temperature and solid volume fraction profiles are presented for representative parameters. The numerical results show that the transient solidification and remelting in the centrifugal force field depend greatly on the infiltration kinetics and thermodynamics of the composite. The regional extent of the eutectic solid metal and its solid volume fraction increase with the moving of the infiltration front. The speed of the moving infiltration and remelting fronts decrease with the decreasing of porosity and rotational speed, but the speed difference between the moving fronts and the regional extend of the eutectic solid metal increases with the decreasing of porosity and decreases with the decreasing of rotational speed.