4145
The feedstock exhibited minor changes to size distribution , bulk composition , and hardness with reuse , but significant changes to particle morphology , microstructure , magnetic properties , surface composition , and oxide thickness .
 feedstock, distribution, composition, hardness, particle, morphology, microstructure, properties, surface, composition, oxide
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:
 feedstock, distribution, composition, hardness, particle, morphology, microstructure, properties, surface, composition, oxide