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Based on these properties , Ti alloys are used as a ‘ workhorse ’ material in the aerospace industry such as engine blades , landing gear assemblies , large structural parts , airframe and drums etc .
 concept or principle: properties; material: Ti alloys; material: as; material: material; application: aerospace industry; material: as; machine or equipment: gear
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:
 concept or principle: properties; material: Ti alloys; material: as; material: material; application: aerospace industry; material: as; machine or equipment: gear