2) For a 0.46 wt%C Ni-Cr steel plate, show any calculations to support your responses to the following queries:
3) For high technological industries, you evaluate metals and ceramics beyond the Fe-C alloys to more costly applications.
A. For one process, elect three alloying components for Ti alloys to give alpha-gamma
phase from an eutectoid reaction and another process, give three alloying components added to Ti to give alpha-gamma phases near a peritectoid reaction. Be sure to describe each process in not more than three sentences.
B. What alloying elements should you seek for stainless steel to have a bar or plate with martensitic phase, as well as explain why?
C. For a material of the hypersonic plane, liquid Hf-Nb-Ta alloy infuses into a B4C packed bed and reacts to form a HfB2-HfC-Nb3B4-Nb4C3-TaC-Ta3B2 composite or the same boride-carbide precipitates embedded in a Hf-Nb-Ta alloy matrix. Determine the mass of Hf, Nb, and Ta needed to give you 1 kg of Nb3B4 in metal matrix having 50at%Hf- 45at%Nb-5at%T a.
D. What two refractories or ceramics (no metals) must you consider to hold a Hf-Nb melt at 2500°C in preparation for a proper Hf/Nb ratio and a refractory to eventually add Ta to the Hf-Nb alloy in a subsequent melting of the Hf-Nb-Ta alloy at 3500°C?
E. A hafnium-niobium melt contained in a graphite or carbon crucible (1 cm thick and 5 cm inner diameter) reacts to form an internal layer composed of HfC and NbC between the Hf-Nb liquid and the internal, graphite crucible. The figure below gives the diffusion coefficients of carbon in cm2/s for HfC, TaC, NbC and ZrC.
F. From the Ta-C phase diagram, below, give the three-phase reactions for a eutectic,
peritectic, peritectoid, congruent, and euctectoid reactions along with their respective temperatures at which they occur.
4) . A Ta2O5 semiconductor at temperatures greater than 1000°C exists with doubly- charged, oxygen vacancies. Your engineering colleague argues strongly that these oxygen ionic defects convert the tantalate lattice into a p-type semiconductor – is he correct and give reasoning?
B. Is the semiconductor n-type or p-type, if Al2O3 is added, instead of Ta2O5, to the NbO lattice and give your reasoning?