1299
However , the formation mechanisms of these grain structures have not been well understood under rapid solidification conditions , especially for AM of superalloys .
 concept or principle: grain structures; manufacturing process: rapid solidification; manufacturing process: AM; material: superalloys
Given options, please tell me the categories of all the listed entity words.Output format is "type1: word1; type2: word2". 
Option: manufacturing standard, machanical property, manufacturing process, material, engineering feature, process parameter, machine or equipment, application, process characterization, enabling technology, biomedical, concept or principle 
Text: {0} 
 Entities: grain structures, rapid solidification, AM, superalloys 
Answer:
 concept or principle: grain structures; manufacturing process: rapid solidification; manufacturing process: AM; material: superalloys