Using the phase diagram below, for an alloy with the composition 30 wt% Pb-70 wt% Mg at 200°C, determine the phases present and the phase compositions (in wt% Pb) 

What is the maximum stress at the tip of an internal crack having a radius of curvature of 3×10^-4 mm and a crack length of 2×10^-2 mm when a tensile stress of 60 MPa is applied?

An alloy of composition 60 wt% Pb - 40 wt% Mg is heated to 300°C.  Using the same phase diagram for Mg-Pb as above, what is the composition (in wt% Pb) of the α phase? 

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Using the phase diagram above, for the same alloy as in the previous question (60 wt% Pb-40 wt% Mg at 300°C), what is the mass fraction of the α phase? 

Your final answer should be in decimal format, *.**

A steel component must not fail when a tensile stress of 2500 MPa is applied.  Determine the maximum allowable surface crack length in nm if the surface energy of steel is 0.20 J/m².  Assume a modulus of elasticity of 200 GPa. Round up your answer to one decimal place.

Your final answer should be in the format *.*

What measures may be taken to increase the resistance to fatigue of a metal alloy?

Give the approximate temperature, in Kelvin, at which creep deformation becomes an important consideration for titanium. The melting temperature of titanium is 1,668°C. Round your answer to one decimal place.

Your final answer should be in the format ***.*