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In this study , the microstructure , residual stress , and mechanical properties of the aB-printed specimen and specimens annealed at 773–1573 K for 2 h were compared .
 concept or principle: microstructure; machanical property: residual stress; concept or principle: mechanical properties; material: K
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: microstructure, residual stress, mechanical properties, K 
Answer:
 concept or principle: microstructure; machanical property: residual stress; concept or principle: mechanical properties; material: K