Among the following statements the wrong one is a At point A

Among the following statements, the wrong one is. a) At point A, the alloy has a composition of 60 wt% Ni and is a solid (alpha phase) b) For a 40 wt%Ni composition, upon cooling from 1500 degree C to 1000 degree C, the liquidus line is crossed before the solidus line c) Copper (Cu) has a higher melting temperature than Nickel (Ni) d) For this system, complete solid solubility exists between Copper and Nickel. The grain boundaries in polycrystalline materials can be revealed by: a) cold working b) etching c) higher magnification d) x-ray diffraction e) colonoscopy Which of the following is FALSE regarding the non-equilibrium cooling of isomorphous alloys (e.g., Cu-Ni system): a) Cored structures will be formed b) The alloy may commence melting at a temperature below the equilibrium solidus line c) The center of the grain is rich in the low-melting element d) Non-equilibrium sample can be modified by a homogenization heat treatment. e) It is different from equilibrium cooling

Solution

15) C

Here copper melting temperature is 1085 c and nickel melting temperature is 1453 c. so copper melting temperature is less than melting temperature of nickel.

16) b

The grain boundaries of polycrystalline materials can be seen by etching (acid etching) process.

17) c

In non-equlibrium cooling cored structres will form but center of core is rich in high melting temperature element.