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Common methods for making porous NiTi structures are based on powder metallurgy and self-propagating high temperature synthesis of a mixture of elemental powders or pre-alloyed NiTi powder with space holding materials .
 machanical property: porous; material: NiTi; manufacturing process: powder metallurgy; process parameter: temperature; material: powders; material: NiTi; concept or principle: materials
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:
 machanical property: porous; material: NiTi; manufacturing process: powder metallurgy; process parameter: temperature; material: powders; material: NiTi; concept or principle: materials