Transcribed Image Text: Q1/ Aluminum is diffused into pure silicon to make a semiconductor
material. How long should be the silicon be heated at 1300°C in contact
with the aluminum such that the aluminum concentration at 0.01 mm
below the surface of silicon.
Q= 80 000 cal /mol. X=V Dt
X= distance. t = time. D= Diffusion coefficient. R= gas constant =
(Take :- Do for Al in Si is 8 cm²/sec.
%3D
cal/mol.°K
Q2/ The following results were obtained from a tensile test of a steel. The
test piece had a diameter of 10mm and a gauge length of 50mm. plot the
load extension graph and determine (a) the tensile strength . (b) the
fracture stress. (c) the tensile modulus.
Load
5
10
15
20
25
30
32
28
KN
0 0.01 0.03 0.05 |0.07 0.08 | 0.1 0.15 0.25
(fracture)
Ext.
mm
