380
However , it is hard to ensure the two different wires melt synchronously under the heat of one single arc , so the desired microstructures with γ ( TiAl ) phase and α2 ( Ti3Al ) phase are hard to obtain .
 melt, heat, arc, microstructures, phase, phase
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:
 melt, heat, arc, microstructures, phase, phase