Re: What happens to the tension in a spring when it is melted?

Assuming you formed the ceramic around the spring while it was under tension, 
and then melted the spring while it was under tension, the whereabouts of the 
tension is not an issue to be concerned with.  The difficulty has to do with 
deciding what is under tension.

When you chose to form a ceramic around your spring, which was already under 
tension, you introduced an contact surface between the ceramic and the spring.  
While the spring and the tension are unchanged there are no forces, compression 
or tension, between the spring and the ceramic.  If the tension is increased, 
compression occurs between the ceramic and the spring to oppose the change and 
there may be minor tensile forces depending upon the extent to which the 
ceramic and spring materials adhere.  If the tension is decreased, compressive 
and tensile forces occur again, though oriented in the opposite directions.

For the case where the tension is unchanged and the spring is melted, the 
connection to the mass (or the basis of the original tension) will be severed 
at or near the surface of the ceramic and there is no basis for compressive or 
tensile forces between the ceramic and the melted spring.

In essence, when you formed a ceramic about your spring, you no longer had a 
spring, in the usual sense.

The best references are still high school and college physics textbooks, though 
you may not find your specific question addressed there.  Introductory 
materials textbooks might also give you background on the sort of environment 
imposed when the ceramic was formed about the spring.

Thanks for your question.

sid