Lecture 9 - Characterization of AM Materials

Question 1

What is neutron diffraction?

Answer 1

nondestructive evaluation of macro-residual stresses, phase, deformation behavior

Question 2

what is x-ray computed tomography (CT)?

Answer 2

nondestructive evaluation of porosity/defects, geometry/dimension, deformation, surface roughness, particle size

Question 3

what is synchrotron x-ray diffraction?

Answer 3

nondestructive evaluation of macro and micro residual stresses, phases, pores, deformation behavior

Question 4

what techniques can be used to analyze prints during 3d printing?

Answer 4

thermal imaging, x-rays, and high-speed camera

Question 5

what is optical imaging?

Answer 5

large scale imaging

Question 6

what two processes measure grain orientation, dislocations, and phases?

Answer 6

scanning electron microscopy
electron back scatter diffraction

Question 7

what is transmission electron micrscopy?

Answer 7

length scale <1 micrometer

Question 8

What neutron facility is at Los Alamos National Lab?

Answer 8

Spectrometer for Materials Research at Temperature and Stress

Question 9

What is the wavelength of LANSCE generated neutrons?

Answer 9

0.5 to 7.5 Å

Question 10

What is the minimum size of samples at LANSCE?

Answer 10

one millimeter

Question 11

What are four characteristics of cell/grain boundaries?

Answer 11

are imperfections
are more susceptible to etching
may be revealed as dark lines
change in crystal orientation across boundary

Question 12

What is the optical light resolution?

Answer 12

0.1 µm

Question 13

What wavelengths do the human eye detect?

Answer 13

380nm-700nm

Question 14

What are three characteristics of electron microscopy?

Answer 14

wavelength ~ 0.003nm
atomic resolution possible
focused by magnetic lenses

Question 15

What does electron backscatter diffraction depend on?

Answer 15

beam size, scan step size

Question 16

What does transmission electron microscopy require of its samples?

Answer 16

sophisticated preparation (thickness <0.25 µm)

Question 17

Which technique is the most indispensable for characterization of printing defects?

Answer 17

x-ray computed tomography

Question 18

What do neutron or x-ray diffraction techniques characterize?

Answer 18

residual stresses
pores
other microstructures

Question 19

What do in operando characterizations do?

Answer 19

understand the fundamental sciences of laser-material interactions

Question 20

What properties are not investigated using these means?

Answer 20

mechanical, thermal, electrical properties

Question 21

What destructive evaluations are also used?

Answer 21

electron backscatter diffraction
multiscale characterizations

Question 22

what are the neutron diffraction facilities?

Answer 22

Los Alamos
Oak Ridge

Question 23

what is the best way to ensure that your image pops up on ct?

Answer 23

use elements with low attenuation coefficient

Question 24

how do you take a ct scan?

Answer 24

rotate part 360 degrees and take sample
combine samples into 3d image

Question 25

What is the typical resolution of CT scan?

Answer 25

1 µm

Question 26

What is CT scan based on?

Answer 26

absorption

Question 27

What is synchrotron based on?

Answer 27

transmission

Question 28

What can synchrotron x-rays pick up?

Answer 28

texture, dislocation

Question 29

which planes are parallel to incident beam in TEM?

Answer 29

diffracting atomic planes

Question 30

What does deformation measure?

Answer 30

lattice strain and stresses

Question 31

What does elastic modulus depend on?

Answer 31

grain boundary direction

Question 32

how do you measure the stress?

Answer 32

measure the strain and convert using elastic modulus

Question 33

what is pyrometry?

Answer 33

determination of temperature by analyzing wavelengths of thermal radiation emissions

Question 34

What does EBSD show?

Answer 34

grain orientation

Question 35

what are the three different modes of TEM?

Answer 35

bright-field, dark-field, weak-beam

Question 36

What does “in operando” mean?

Answer 36

Machine has measurement tools in situ