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During solidification of many so-called high-performance engineering alloys , such as 6000 and 7000 series aluminum alloys , which are also unweldable autogenously , volumetric solidification shrinkage and thermal contraction produces voids and cracks .
 concept or principle: solidification; application: engineering; material: alloys; material: as; material: aluminum alloys; concept or principle: solidification shrinkage; concept or principle: contraction; concept or principle: voids
Given options, please tell me the categories of all the listed entity words.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} 
 Entities: solidification, engineering, alloys, as, aluminum alloys, solidification shrinkage, contraction, voids 
Answer:
 concept or principle: solidification; application: engineering; material: alloys; material: as; material: aluminum alloys; concept or principle: solidification shrinkage; concept or principle: contraction; concept or principle: voids