140
Remanufacturing and Advanced Machining
Materials that change color are termed “chromogenic” or “chromotropic,”
sometimes also called chameleonic because they reversibly change color as a
response to changes in environmental conditions (Ferrara and Bengisu, 2014). In
certain applications, a permanent color change is preferred, which is also possible
with some chromogenic materials. The technical principle by which these materials
function can be explained by an alteration in the equilibrium of electrons caused by
a stimulus, with a consequent modification of reflectance, absorption, emission, or
transmission. This process, named chromism, involves a change in the microstructure or electronic state of substances, mostly in conjugated polymers (Ferrara and
Bengisu, 2014).
Among the most interesting functional nanomaterials, Fe–Pd ferromagnetic
alloys are worthy of attention due to their excellent functional properties such as high
uniaxial magnetic anisotropy, high Kerr rotation, magnetic shape memory effect,
high corrosion resistance, and biocompatibility. Prida et al. (2012) underline that in
addition to thin films, Fe–Pd nanowires and antidots are also promising smart materials suitable for magnetic shape memory nanoactuators, magnetocaloric or highdensity data storage micro-devices.
Guo et al. (2020) describe a group of smart materials with the ability to sense four
common biomolecules, namely glucose, nucleic acids, proteins, and enzymes. The
authors point out that smart materials, such as hydrogels, or various nanomaterials
like gold nanoparticles, quantum dots, carbon nanotubes, and graphene have been
widely used for applications in biosensing. Photonic crystals, i.e., periodic micro- or
nanostructures that can control the reflection of light, provide an excellent platform
for biosensing with visible readout to report target analytes. Molecularly imprinting polymers comprise a class of materials with a special recognition site to bind
with imprinted molecules used for detection of various biomolecules such as proteins and enzymes, based on responsive changes in refractive index and volume.
Especially sensitive materials, such as electrochemical, optical, thermal, piezoelectric, and impedimetric sensors, as well as interferometric biosensors have been
widely employed as diagnostic platforms.
3.4 SUPERPLASTICITY AND ITS APPLICATION
TO METAL FORMING
According to Humphreys et al. (2017), superplastic materials are polycrystalline solids that have the ability to exhibit unusually large ductilities and often
elongations of several hundred percent when deformed in uniaxial tension, and
exceptionally, even up to several thousand percent, in contrast to a normal ductile metal that will fail by necking after an elongation of less than 50%. This is
illustrated in Figure 3.3 with two strain-stress diagrams. The authors name a
wide variety of metals, alloys, and even ceramics that can be made superplastic.
Production of superplastic microstructures in any crystalline material exploits
the principles of recrystallization and grain growth, as well as stability of such
a microstructure during subsequent high-temperature deformation (Humphreys
et al., 2017).
Remanufacturing and Advanced Machining
Materials that change color are termed “chromogenic” or “chromotropic,”
sometimes also called chameleonic because they reversibly change color as a
response to changes in environmental conditions (Ferrara and Bengisu, 2014). In
certain applications, a permanent color change is preferred, which is also possible
with some chromogenic materials. The technical principle by which these materials
function can be explained by an alteration in the equilibrium of electrons caused by
a stimulus, with a consequent modification of reflectance, absorption, emission, or
transmission. This process, named chromism, involves a change in the microstructure or electronic state of substances, mostly in conjugated polymers (Ferrara and
Bengisu, 2014).
Among the most interesting functional nanomaterials, Fe–Pd ferromagnetic
alloys are worthy of attention due to their excellent functional properties such as high
uniaxial magnetic anisotropy, high Kerr rotation, magnetic shape memory effect,
high corrosion resistance, and biocompatibility. Prida et al. (2012) underline that in
addition to thin films, Fe–Pd nanowires and antidots are also promising smart materials suitable for magnetic shape memory nanoactuators, magnetocaloric or highdensity data storage micro-devices.
Guo et al. (2020) describe a group of smart materials with the ability to sense four
common biomolecules, namely glucose, nucleic acids, proteins, and enzymes. The
authors point out that smart materials, such as hydrogels, or various nanomaterials
like gold nanoparticles, quantum dots, carbon nanotubes, and graphene have been
widely used for applications in biosensing. Photonic crystals, i.e., periodic micro- or
nanostructures that can control the reflection of light, provide an excellent platform
for biosensing with visible readout to report target analytes. Molecularly imprinting polymers comprise a class of materials with a special recognition site to bind
with imprinted molecules used for detection of various biomolecules such as proteins and enzymes, based on responsive changes in refractive index and volume.
Especially sensitive materials, such as electrochemical, optical, thermal, piezoelectric, and impedimetric sensors, as well as interferometric biosensors have been
widely employed as diagnostic platforms.
3.4 SUPERPLASTICITY AND ITS APPLICATION
TO METAL FORMING
According to Humphreys et al. (2017), superplastic materials are polycrystalline solids that have the ability to exhibit unusually large ductilities and often
elongations of several hundred percent when deformed in uniaxial tension, and
exceptionally, even up to several thousand percent, in contrast to a normal ductile metal that will fail by necking after an elongation of less than 50%. This is
illustrated in Figure 3.3 with two strain-stress diagrams. The authors name a
wide variety of metals, alloys, and even ceramics that can be made superplastic.
Production of superplastic microstructures in any crystalline material exploits
the principles of recrystallization and grain growth, as well as stability of such
a microstructure during subsequent high-temperature deformation (Humphreys
et al., 2017).