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Microstructural characterization was carried out on AISI 17-4 PH stainless steel fabricated by selective laser melting ( SLM ) in an argon environment .
 process characterization: Microstructural characterization; material: 17-4 PH stainless steel; manufacturing process: selective laser melting; manufacturing process: SLM; material: argon
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: Microstructural characterization, 17-4 PH stainless steel, selective laser melting, SLM, argon 
Answer:
 process characterization: Microstructural characterization; material: 17-4 PH stainless steel; manufacturing process: selective laser melting; manufacturing process: SLM; material: argon