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Gas tungsten arc welding ( GTAW ) provides the heat source for this new approach , combined with in-situ alloying through separate feeding of commercially pure Ti and Al wires into the weld pool .
 manufacturing process: Gas tungsten arc welding; manufacturing process: GTAW; concept or principle: heat source; concept or principle: in-situ; engineering feature: alloying; material: Ti; material: Al; concept or principle: weld pool
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:
 manufacturing process: Gas tungsten arc welding; manufacturing process: GTAW; concept or principle: heat source; concept or principle: in-situ; engineering feature: alloying; material: Ti; material: Al; concept or principle: weld pool