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Therefore , in the current investigation , a comprehensive microstructural characterization and mechanical properties ( tensile , fatigue and impact toughness ) evaluation of nickel alloy 718 AM by the laser powder bed fusion ( L-PBF ) technique have been performed .
 microstructural characterization, mechanical properties, tensile, fatigue, impact, nickel alloy, AM, laser powder bed fusion, L-PBF
Please list all entity words in the text that fit the category. Output format is "word1, 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} 
Answer:
 microstructural characterization, mechanical properties, tensile, fatigue, impact, nickel alloy, AM, laser powder bed fusion, L-PBF