The effects of grain refining parameters on microstructure of AM60B magnesium alloy with MgCO3 were investigated and then a refining technique was developed.Simultaneously,the corresponding mechanisms were discussed.T...The effects of grain refining parameters on microstructure of AM60B magnesium alloy with MgCO3 were investigated and then a refining technique was developed.Simultaneously,the corresponding mechanisms were discussed.The results indicate that increasing addition temperature of MgCO3 or pouring temperature is beneficial for obtaining fine grains.There is an optimal addition amount of 1.2%at the addition temperature of 790°C.Prolonging holding time at 790°C will increase grain size.The grain refining technique that 1.2%MgCO3 is added at 790°C followed by holding for 10 min and pouring can decrease the grain size from 348μm of the un-refined alloy to 69μm.The nucleation substrates are actually the Al4C3 particles formed from reactions between the MgCO3 and alloying elements in the melt.Besides the heterogeneous nucleation regime,growth restriction of the Al4C3 particles agglomerated at growing front is the other mechanism.展开更多
Herein, three kinds of Li2CO3 and two kinds of MgCO3·3H2O crystals are easily synthesized in a homogeneouslike organic phase. The morphology and size of synthesized crystals are controllable and adjustable in the...Herein, three kinds of Li2CO3 and two kinds of MgCO3·3H2O crystals are easily synthesized in a homogeneouslike organic phase. The morphology and size of synthesized crystals are controllable and adjustable in the single organic phase, with the morphology of Li2CO3 ranging from micro-flaky, flower to nanobranch, MgCO3·3H2O rangi ng from nanosphere to nanorod. Compared with coupled reacti on and solve nt extraction process, of which the crystallization process occurred in the interface of two phase, our proposed method made it possible that the crystallization process occurred in the single organic phase, which resulted in better crystal morphology. Moreover, the formation mechanism of different crystal morphologies is discussed, the results showed that the crystals in micron size and nano size are involved in two crystallization mechanism, the micron particles in the form of flake and flower-like is a typical radial growth, which means that the growth occurs by diffusion around a nucleus as starting point, while the reaction model for small particles should be similar to a water-in-oil structure. As the reaction carried out, the crystal should be restricted in a constrained organic structure.展开更多
基金Project(G2010CB635106)supported by the National Basic Research Program of ChinaProject(NCET-10-0023) supported by the Program for New Century Excellent Talents in University of China
文摘The effects of grain refining parameters on microstructure of AM60B magnesium alloy with MgCO3 were investigated and then a refining technique was developed.Simultaneously,the corresponding mechanisms were discussed.The results indicate that increasing addition temperature of MgCO3 or pouring temperature is beneficial for obtaining fine grains.There is an optimal addition amount of 1.2%at the addition temperature of 790°C.Prolonging holding time at 790°C will increase grain size.The grain refining technique that 1.2%MgCO3 is added at 790°C followed by holding for 10 min and pouring can decrease the grain size from 348μm of the un-refined alloy to 69μm.The nucleation substrates are actually the Al4C3 particles formed from reactions between the MgCO3 and alloying elements in the melt.Besides the heterogeneous nucleation regime,growth restriction of the Al4C3 particles agglomerated at growing front is the other mechanism.
基金Supported by the National Natural Science Foundation of China(U1607118)
文摘Herein, three kinds of Li2CO3 and two kinds of MgCO3·3H2O crystals are easily synthesized in a homogeneouslike organic phase. The morphology and size of synthesized crystals are controllable and adjustable in the single organic phase, with the morphology of Li2CO3 ranging from micro-flaky, flower to nanobranch, MgCO3·3H2O rangi ng from nanosphere to nanorod. Compared with coupled reacti on and solve nt extraction process, of which the crystallization process occurred in the interface of two phase, our proposed method made it possible that the crystallization process occurred in the single organic phase, which resulted in better crystal morphology. Moreover, the formation mechanism of different crystal morphologies is discussed, the results showed that the crystals in micron size and nano size are involved in two crystallization mechanism, the micron particles in the form of flake and flower-like is a typical radial growth, which means that the growth occurs by diffusion around a nucleus as starting point, while the reaction model for small particles should be similar to a water-in-oil structure. As the reaction carried out, the crystal should be restricted in a constrained organic structure.
