Question

1. State the main benefit of using the Oxide Dispersion Strengthened (ODS) superalloys.

2.What makes TCP phase undesirable in superalloys? Give two reasons.

Answer 1

1. Oxide Dispersion Strengthened (ODS) superalloys have thefollowing advantages

a. These alloys develop a stable protective oxide layer that protects the alloy from erosion.

b. These alloys favours the formation of thin-walled strutures.

c. These are resistant to harsh whether condition due to foration of protective oxide layer that protects the alloy from erosion.

d.They have low production and maintanience cost etc.

2: Formation of Topologically Close-Packed(TCP) phase is a charact eristics feature in super alloys that depends on temperature alloy composition etc. Different types of TCP phases found in super alloys are gamma - , sigma - , mu - etc. PCP phases have needle like or single plane microstructure.

TCP phase is undesirable because

a.they effect on mechanical properties of alloy like ductility, creeping properties etc.

b.They stimulate the formation of crack due to their brittle nature.

c. Theycombine with gamma - and gamma'- strengthening units in a wasteful manner to reduce the creeping strength.