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Microstructures of the aB-built and heat treated samples were investigated using optical and scanning electron microscopes , X-ray diffraction , and electron backscattered diffraction techniques .
 Microstructures, heat, samples, optical, scanning electron microscopes, X-ray diffraction, diffraction
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:
 Microstructures, heat, samples, optical, scanning electron microscopes, X-ray diffraction, diffraction