1. College of Materials Science and Engineering Chongqing University Chongqing 400044 P. R. China
2. Chongqing Key Laboratory of Vanadium‐Titanium Metallurgy and New Materials Chongqing University Chongqing 400044 P. R. China
3. Spectris Instrumentation and Systems Shanghai Ltd. Shanghai 200233 P. R. China