Determine if the following sentences are true or false Regar

Determine if the following sentences are true or false: Regarding impact toughness, BCC structured metals are more sensitive to temperature transition compare to FCC structured metals. Materials with lower transition temperatures are more useful in engineering applications as they can be used in wider temperature range. The following picture shows the fracture surface of a materials with very low toughness after impact test:

Solution

1) If we compare both FCC and BCC the packing efficiency is 74 for FCC and 68 for BCC.which means that the atoms are more closely packed in FCC atom compare to BCC.Therefore, the void spaces is more in BCC which will easily effected to the temperature, and the impact toughness also decreases for BCC compared to FCC.

therfore the statement is TRUE

2) number of materials wil change their behaviour from ductile to brittle based on the transition temperature.at low transistion temperature more number of materials will exhibit ductile nature with large temperature range.Therefore these are used for engineering applications.

therfore the statement is TRUE

3) As the grain size is larger, the toughness value increases.But the given statement is opposite.

therfore the statement is FALSE