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The present study investigated to what extent this strategy affected the surface roughness , relative density , microstructure and mechanical properties of Ti-6Al-4 V parts .
 machanical property: surface roughness; machanical property: relative density; concept or principle: microstructure; concept or principle: mechanical properties; material: Ti-6Al-4 V
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: surface roughness, relative density, microstructure, mechanical properties, Ti-6Al-4 V 
Answer:
 machanical property: surface roughness; machanical property: relative density; concept or principle: microstructure; concept or principle: mechanical properties; material: Ti-6Al-4 V