Co-reporter:Tian-Yu Liu;Jie Sun;Cheng Sheng;Qi-Xin Wang;Yun-Hu Zhang
Advances in Manufacturing 2017 Volume 5( Issue 2) pp:143-148
Publication Date(Web):19 May 2017
DOI:10.1007/s40436-017-0175-8
Solidification experiments were carried out in Al-Cu (w(Cu) = 5%) alloy to investigate the influence of pulse magneto-oscillation (PMO) on the efficiency of the Al3Ti1B refining agent at high superheat. The experimental solidification results show that the degree of superheat has remarkable influence on the efficiency of the grain refiner. However, the application of PMO has the potential to reduce the influence of superheat variation on the efficiency of the grain refiner. Finally, the mechanism underlying this phenomenon is discussed by performing a numerical simulation to show the forced flow inside the melt caused by PMO.
Co-reporter:Jianhong Ma, Jie Li, Yulai Gao, Qijie Zhai
Materials Letters 2009 Volume 63(Issue 1) pp:142-144
Publication Date(Web):15 January 2009
DOI:10.1016/j.matlet.2008.09.036
A comparative study on grain refinement of pure Al by applying electric current pulse (ECP) at different positions in the mould was carried out. The experimental results showed that fine equiaxed grains were generated by exerting ECP at different electrode positions, and the highest proportion of fine equiaxed grain area was obtained when ECP was applied at the upper and lower lateral wall of the mould. The refinement mechanism of exerting ECP and the reasons of different refining efficiency with various ECP employing modes were also discussed.
Co-reporter:Xiliang Liao, Qijie Zhai, Jun Luo, Wenjie Chen, Yongyong Gong
Acta Materialia 2007 Volume 55(Issue 9) pp:3103-3109
Publication Date(Web):May 2007
DOI:10.1016/j.actamat.2007.01.014
Abstract
The refining mechanism of the electric current pulse (ECP) on the solidification structure of pure aluminum is systematically investigated by properly designed experiments. The experiment results show that the solidification structure cannot be refined by exerting an ECP on the high temperature liquid phase, indicating that the ECP has no inoculation effect on the liquid metal. The ECP has also no obvious influence on the solidification structure when it is applied during crystal growth, showing that the ECP cannot cause melting or break off the growing crystal. However, the very fine macrostructure is obtained by applying an ECP during the nucleation of the melt. The reason is that the ECP makes the crystal nuclei formed on the wall of the mould fall off and move freely in the molten metal, promoting the multiplication of crystal nuclei.
Co-reporter:Yu-Lai Gao, Qiu-Shu Li, Yong-Yong Gong, Qi-Jie Zhai
Materials Letters 2007 Volume 61(Issue 18) pp:4011-4014
Publication Date(Web):July 2007
DOI:10.1016/j.matlet.2007.01.007
A comparative study on the structural transformation of low-melting pure Al and high-melting 1Cr18Ni9Ti stainless steel under external pulsed magnetic field was carried out. The results showed that totally equiaxed grains were produced for pure Al, however, only thin columnar grains were generated for stainless steel even treated with higher magnetic intensity. It is deemed that grain refinement can be attributed to the heterogeneous nucleus created on the mould wall as well as their falling by the oscillating resulting from the magnetic field. In contrast, a dense chilling layer was generated at the primary solidification stage of the stainless steel due to the large temperature gradient between the high temperature melt and the mould and accordingly the nucleus falling was prevented. Therefore, only dendrites refinement possibly occurred.
Co-reporter:Wan-Bing Guan, Yu-Lai Gao, Qi-Jie Zhai, Kuang-Di Xu
Materials Letters 2005 Volume 59(Issue 13) pp:1701-1704
Publication Date(Web):June 2005
DOI:10.1016/j.matlet.2005.01.055
The effects of droplet size and cooling rate on the undercooling of droplet solidification were investigated in the present paper, and the relation between the droplet size and cooling rate versus the undercooling was obtained by DSC. It is shown that the undercooling increases with the decrease of droplet size and increase of cooling rate. Moreover, it is interesting to find that the undercooling and its change rate increase significantly with the droplet size below 20 μm on condition that the cooling rate remains unchanged. Additionally, it is a novelty that the change trend of undercooling decreases with the increasing cooling rate.
