Large and heavy castings are made by ?

a) green sand moulding.

(b) dry sand moulding.

(c) pressure moulding

(d) machine moulding

What is an isomorphous system ? Give an example.

The term isomorphous system is related to phase diagram. Isomorphicity means having same crystal structure or complete solubility for all compositions. The copper nickel system is an example of isomorphous system.

What is peritectic reaction ?

A reaction where in, upon cooling a solid and a liquid phase transform isothermally and reversibly to a solid phase having different composition is called a peritectic reaction.

Define Burger's Vector.

Burger vector is defined as plastic displacement produced by the dislocation. It describes both magnitude and direction of slip.

State the Griffith criterion for crack propagation in brittle solid.

Brittle fracture is the failure of a material without apparent plastic deformation. If the broken pieces after a brittle fracture are fitted together, lies the original shape and dimensions of specimen are restored.

Griffith has postulated a criterion for the propagation of pre-existing crack in brittle material (glass). Griffith postulated that brittle fracture occured when the energy release rate during crack growth exceeded the rate that energy was required.
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