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Due to the fast solidification rate , a large number of acicular α′ forms in fusion zone ( FZ ) , leading to the highest microhardness .
 process parameter: solidification rate; concept or principle: fusion zone; concept or principle: FZ; concept or principle: microhardness
Please list all entity words in the text that fit the category.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} 
Answer:
 process parameter: solidification rate; concept or principle: fusion zone; concept or principle: FZ; concept or principle: microhardness