Group I Group II P. Grain size strengthening 1. Orowan looping Q. Work hardening 2. Suzuki interaction R. Dispersion strengthening 3. Lomer-Cottrell barrier S. Solid solution hardening 4. Dislocation pileup at grain boundaries
The question asks to match strengthening methods in metallic alloys (Group I) with their corresponding mechanisms (Group II).
Matching Strengthening Methods and Mechanisms
We need to find the correct pairings based on established metallurgical principles:
- P. Grain size strengthening: This method relies on reducing the average grain size. Smaller grains present more grain boundaries, which act as barriers to dislocation movement. Dislocations moving within a grain must eventually encounter a boundary, requiring them to change direction or initiate slip in the next grain, which is energetically costly. Thus, grain size strengthening is primarily achieved through 4. Dislocation pileup at grain boundaries.
- Q. Work hardening: Also known as strain hardening, this occurs when a metal is plastically deformed. The deformation process generates and tangles dislocations, increasing their density. These tangled dislocations impede each other's motion. Specific configurations like 3. Lomer-Cottrell barriers can form, hindering further slip and strengthening the material.
- R. Dispersion strengthening: This involves adding fine, stable, second-phase particles (dispersoids) into the metal matrix. These particles act as obstacles to dislocation motion. Dislocations must either cut through the particles or bow around them. The process of bowing around uncut obstacles is known as 1. Orowan looping.
- S. Solid solution hardening: This mechanism strengthens the alloy by dissolving solute atoms into the solvent matrix. These solute atoms distort the crystal lattice and interact with dislocations, creating localized stress fields that impede dislocation movement. While 'Suzuki interaction' typically relates to grain boundary phenomena or precipitation effects, in the context of the given options and the process of elimination, it is the designated match for solid solution hardening effects described in this question context, likely referring to solute atom interactions affecting dislocation mobility or grain boundary behavior influenced by solutes. Hence, the match is 2. Suzuki interaction.
Final Matched Pairs
Based on the analysis, the correct matches are:
| Group I (Method) | Group II (Mechanism) |
|---|---|
| P. Grain size strengthening | 4. Dislocation pileup at grain boundaries |
| Q. Work hardening | 3. Lomer-Cottrell barrier |
| R. Dispersion strengthening | 1. Orowan looping |
| S. Solid solution hardening | 2. Suzuki interaction |
This corresponds to the pairing P-4, Q-3, R-1, S-2.
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.
