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Advanced Physical Metallurgy Advanced Physical Metallurgy
“ “ Amorphous Materials Amorphous Materials ” ”
Eun Eun Soo Soo Park Park
Office: 33-316
Telephone: 880-7221
Email: espark@snu.ac.kr
Office hours: by an appointment
2009 spring
03. 30. 2009
T
f= T
gTg
= fictive temperature, T
fGlass transition
: region over which change of slope occurs : “pseudo” second order phase transition
Contents for previous class
Contents for previous class
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Contents for previous class Contents for previous class
• • T T
ggdepends on thermal history. depends on thermal history.
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Specific heat capacity (a.k.a. Specific heat)
• symbolized as c, units in J/g°C
• It’s the heat required to raise 1 gram of a substance by 1 °C
Heat capacity
• calculated by c x m, units in J/°C
• It’s the heat required to raise the temperature of an object by 1 °C.
Molar heat capacity : units in J/mol °C.
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Differential Thermal Analysis
Differential Thermal Analysis
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DSC Scan
DSC Scan DTA Scan DTA Scan
Low temp. 253 K ~ 973 K
Low temp. 253 K ~ 973 K High temp. 373K ~ 1573 KHigh temp. 373K ~ 1573 K
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Determination of
Determination of T T
gg17
340 360 380 400 420 440
3.152 3.156 3.160 3.164 3.168 3.172 3.176 3.180
7.28 * 10-5
Tg = 385 K
Tx= 415 K
Length (mm)
Temperature (K)
Thermal expansion curve obtained from the rod of Ca65Mg15Zn20 (3 mm in height and 2 mm in diameter).
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Determination of Tg for glasses by dilatometry.
The linear sections below and above Tg are marked green;
Tg is the temperature at the point of intersection of the corresponding red regression lines.
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The Dynamic Mechanical Analysis is a high precision technique for measuring the viscoelastic properties of materials. It consists in applying a sinusoidal deformation to a specimen of material and measuring the resulting force transmitted through the specimen.
Specimen
Applied displacement
Amplitude
Resulting force
Time
Loss angle δ
F D
