Material hardness is proportional to the ductility. 2. ___ Materials that are significantly cold worked tend to have a lower recrystallization temperature. 3. ___ Ductile-brittle transition temperature (DBTT) is commonly seen in BCC metals. 4. ___ Strain hardening is a result of increased dislocation density. 5. ___ Non-ferrous metals, such as Al and Cu, do not have an endurance limit. 6. ___ Solid solution refers to a mixture of two or more metals in the liquid state. 7. ___ Eutectic alloys solidify at a constant temperature. 8. ___ All aluminum alloys can be age hardened. 9. ___ Over-aging can further strengthen the age-hardened alloys. 10. ___ Martensitic transformation is a diffusionless phase transformation. 11. ___ Hardenability and hardness refer to the same material property. 12. ___ Hardness of a heat treated steel is generally proportional to the carbon content. 13. ___ Martensitic transformation is exclusive to ferrous materials. 14. ___ Gray cast iron contains graphites in the microstructure. 15. ___ 316 stainless steel is more ductile than plain carbon steels. 16. ___ Magnesium is lighter and generally more ductile than aluminum. 17. ___ Bronze (Cu-Zn) and brass (Cu-Sn) are solid solution strengthened coppers.