financial support of China National Funds for Distinguished Young Scientists (51125002);Natural Science Foundation of China(Grant no.51071127);Free Research Fund of State Key Lab.of Solidication Processing (09-QZ-2008and 24-TZ-2009);111 project (B08040);Huo Ying-dong Yong Teacher Fund (111052);Fundamental Research Fund of Northwestern Polytechnical University(JC200801,JC201008);National Basic Research Program of China (973 Program) 2011CB610403