Effect of low-frequency electromagnetic field on the as-cast microstructure of a new super high strength aluminum alloy by horizontal continuous casting
The super high strength aluminum alloy ingots with 100 mm in diameter were cast by the process of low-frequency electromagnetic horizontal continuous casting (LFEHC) and the effect of electromagnet ic field on the as-cast microstructure was studied. Results show that microstructure of the sample prepared by the LFEHC process was greatly refined. Microstructures at the border and the center of the ingots were fine, uniform and rosette-shaped. Electromagnetic frequency plays a key role in microstructure refining. Fine and uniform microstructures can be obtained with optimal electromagnetic frequency. In this experiment, under a frequency of 30 Hz the microstructure was the finest and the most uniform.
Intracrytalline element solubility and mechanical property of a new super-high strength and toughness Al alloy cast under low frequency electromagnetic field
A new superhigh strength and toughness Al alloy (10Zn25Mg25Cu015ZrbalanceAl) was semicontinuously cast on the basis of CREM (casting, refining, electromagnetic), by lowering the electromagnetic frequency to 15～35Hz The differences of microstructure, intracrytalline element solubility and mechanical properties between DC and low frequency electromagnetic casting were investigated The effect of electromagnetic frequency and number of ampere turns on intracrytalline element solubility and mechanical properties were focused on The results show that low frequency electromagnetic cast microstructures of 10Zn25Mg25Cu015ZrbalanceAl alloy are well refined, and intracrytalline element (Zn,Mg and Cu) solubility and mechanical properties are greatly increased It also shows that when the optimum frequency is 15～25Hz and number of ampere turns is 12800～16000A, intracrytalline element (Zn,Mg and Cu) solubility are higher, and mechanical properties are the best The billets were extruded into 12mm bars and their tensile ultimate strength are 780MPa and the elongation are greater than 8% after thermal treatment
General expression for the density effect for the ionization loss of charged particles
The equations for the density-effect correction $\ensuremath{\delta}(X)$ for the ionization loss as given in a previous paper have been extended to the case where $\ensuremath{\delta}({X}_{0})\ensuremath{\equiv}{\ensuremath{\delta}}_{0}g0$. Here ${X}_{0}$ is the lower limit of the range ${X}_{0}lXl{X}_{1}$, where a particularly simple expression for $\ensuremath{\delta}(X)$ applies; $X={log}_{10}(\frac{p}{{m}_{0}c})$, where $p$ is the momentum and ${m}_{0}$ is the mass of the incident particle. The case ${\ensuremath{\delta}}_{0}g0$ applies directly to the calculation of $\ensuremath{\delta}(X)$ for conductors (metals).