中国有色金属学报(英文版)
Transactions of Nonferrous Metals Society of China
| Vol. 11 No. 4 August 2001 |
making thixotropicbillet by SIMA method
（1. School of Materials Science and Engineering,
Harbin Institute of Technology,Harbin 150001, P.R.China;
2. Department of Materials and Chemical Engineering,
Liaoning Institute of Technology,Jinzhou 121001, P.R.China）
Abstract:The effect of SIMA process parameters on LC4 alloy's microstructure and the microstructural evolution of various soaking times have been studied. The results show that effective strain in cold deformation before reheating has a great influence on microstructural evolution. Grain size decreases and its shape also approaches to sphericity with increasing effective strain. The amount of liquid phase increases at grain boundaries and grain shape becomes smooth with increasing heating temperature. The main mechanism of grain coarsening is coalescence when eutectic liquid is rare and not totally distributed at all boundaries. Otherwise the main mechanism of grain coarsening is Ostwald ripening and the connection coarsening is more difficult to perform when the regions are nearly full of eutectic liquid.
Key words: SIMA process; LC4 alloy; microstructure; coarsening mechanism
