Assertion [A]: Refractory BCC metals like W and Mo are less ductile than FCC metals like Ni and Pt at room temperature
Reason [R]: BCC metals have fewer independent slip systems than FCC metals
Evaluating Assertion [A] and Reason [R]
Assertion [A] states that refractory BCC metals like Tungsten (W) and Molybdenum (Mo) are less ductile than FCC metals like Nickel (Ni) and Platinum (Pt) at room temperature. This statement is considered true. BCC metals, particularly refractory ones, often exhibit lower ductility at room temperature compared to FCC metals, which generally display good ductility.
Reason [R] claims that BCC metals have fewer independent slip systems than FCC metals. This statement is considered false. FCC metals possess 12 primary slip systems. While BCC metals have many potential slip systems ({110}, {112}, {123} planes), the statement that they inherently have *fewer* independent slip systems than FCC metals is inaccurate. The factors contributing to ductility differences are more complex than just the number of slip systems.
Since Assertion [A] is true and Reason [R] is false, the correct option is that [A] is true but [R] is false.
Important Questions from Defects Dislocation Stress Field Burgers Vector
- Which one of the following dislocation dissociation reactions is feasible in face-centered cubic metals?
- With reference to edge and screw dislocations, which of the following statements is/are CORRECT?
The Burger's vector of a dislocation in a cubic crystal (with lattice parameter a) is $\frac{a}{2}[110]$ and dislocation line is along $[112]$ direction. The angle (in degrees) between the dislocation line and its Burger's vector is _________
- A plastically deformed metal crystal at low temperature exhibits wavy slip line pattern due to
- The c/a ratio of Zn (hcp) is 1.856. Slip at room temperature occurs most easily on which of the following slip systems in Zn:
Note: In hcp metals, the ideal c/a ratio is 1.633.
