2. Assume you have carbon diffusing into an a-Fe host metal. The diffusion occurs at 900...
1) You find that carbon takes 259 s to diffuse to a concentration of 0.5 wt% at a depth of 0.1 mm in BCC iron if the intitial concentration is 0.2 wt% and the surface is maintained at 1 wt% at 863 K. At temperature 888 what diffusion time will be needed? 2) You find that carbon takes 553 s to diffuse to a concentration of 0.5 wt% at a depth of 0.1 mm in BCC iron if the intitial...
Find the carbon concentration which can be achieved after 19.7 h
at a position 2 mm of a
-iron/carbon alloy with initial concentration of 0.2 wt% C. The
concentration in the surface is maintained at 1.30 wt% C, and the
treatment is conducted at 1000 °C. For diffusion coefficient, use
the diffusion data for
-Fe in Table 6.2 in the textbook.
z
erf(z)
0.85
0.7707
0.90
0.7970
In the carburizing process the steel piece was exposed, at an elevated temperature (900 °C), to an atmosphere rich in a hydrocarbon gas, such as methane CH Surface concentration of carbon is to be maintained at 1.18 wt%. Determine the time (in hours) necessary to achieve a carbon content of 0 68 wt% at a position 0.8 mm below the surface. Initial carbon concentration is 0 18 wt% Take the diffusion coefficient for carbon in iron at 900°C = 1.0...
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Q1a) A high school is launching a recycling campaign for a week. It was found that some students have mixed the scrap steels, polyethylene terephthalate bottles and aluminium cans into a recycle bin. Using understanding of material properties, describe the order of methods, that enable the students to separate all the wastes found in the recycle bin, in a safe way, without causing harmful towards the environment, by using the facilities/ resources found...
Calculate D, diffusion coefficient in m^2/s at the soecified
temperature
tions Determine the carburizing time necessary to achieve a carbon concentration of 0.47 wts at a position 2.1 mm into an iron-carbon alloy that initially contains 0.13 wt%C. The surface concentration is to be maintained at 1.1 wtC. and the treatment is to be conducted at 1180'C. Assume that Do -6,310ms and Q-113 kJ/mol. The table Tabulation of Error Function Values may be useful
A diffusion couple composed of
two silver– gold alloys is formed; these alloys have compositions
of 98 wt% Ag–2 wt% Au and 95 wt% Ag– 5 wt% Au. Determine the time
this diffusion couple must be heated at 750°C (1023 K) in order for
the composition to be 2.5 wt% Au at the 50 μm position into the 2
wt% Au side of the diffusion couple. Preexponential and activation
energy values for Au diffusion in Ag are 8.5 × 10−5...
Please show work for problems 1-4
1. Calculate the activation energy for vacancy formation in aluminum, given that the equilibrium number of vacancies at 500°C (773 K) is 7.57 x10m3. The atomic weight and density (at 500°c) for aluminum are 26.98 g/mol and 2.62 g/cm, respectively 2. What point defects are possible for Al,0, as an impurity in Mgo? How many Al ions must be added to form each of these defects? 3. A sheet of steel 4.5 mm thick...
10. Determine the carburizing time (in seconds) necessary to achieve a carbon concentration of 0.44 wt% at a position 3.0 mm into an iron-carbon alloy that initially contains 0.031 wt% C. The surface concentration is to be maintained at 1.2 wt% C, and the treatment is to be conducted at 1090°C. Assume that DO = 5.1 x 10-5 m2/s and Qd = 154 kJ/mol. You will find the table below useful. Z erf(z) t erf(z) Z erf(z) 0 0.55 1.3...
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you
compare and co describe one industrial application in which steady state diffusion plays an important role, use sketches as needed; (c) An FCC iron-carbon alloy initially containing 0.22 wt% carbon is carburized at an elevated temperature and in an atmosphere wherein the surface carbon concentration is maintained at 1.1 wt% carbon. If after 50.0 hours the concentration of carbon is 0.47 wt% at a position 2.2 mm below the surface, determine...
Determine the carburizing time (in s) necessary to achieve a carbon concentration of 0.44 wt% at a position 1.4 mm into an iron-carbon alloy that initially contains 0.031 wt% C. The surface concentration is to be maintained at 1.2 wt% C, and the treatment is to be conducted at 1130°C. Assume that Do -5.1 x 10-5 m2/s and Qd 154 kJ/mol. You will find the table below useful. erf(z) erf(2)z erf(z) 5633 1.3 0.9340 0.025 0.0282 0.60 0.6039 1.4 0.9523...