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To widen the applications of new materials in additive manufacturing ( AM ) , the traditional method of printing using pre-alloyed powders should be improved because the pre-alloying process is expensive and makes it difficult to adjust the composition of new materials .
 concept or principle: materials; manufacturing process: additive manufacturing; manufacturing process: AM; material: powders; material: be; concept or principle: process; concept or principle: composition; concept or principle: materials
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: materials, additive manufacturing, AM, powders, be, process, composition, materials 
Answer:
 concept or principle: materials; manufacturing process: additive manufacturing; manufacturing process: AM; material: powders; material: be; concept or principle: process; concept or principle: composition; concept or principle: materials