Autonomous Repair Mechanism of Creep Damage in Fe-Au and Fe-Au-B-N Alloys

The autonomous repair mechanism of creep cavitation during high-temperature deformation has been investigated in Fe-Au and Fe-Au-B-N alloys. Combined electron-microscopy techniques and atom probe tomography reveal how the improved creep properties result from Au precipitation within the creep cavities, preferentially formed on grain boundaries...

Tuning the phase transition in transition-metal-based magnetocaloric compounds

Neutron-diffraction experiments on the (Mn,Fe)2(P,Si)-type compounds have shown a site preference of Si atoms in the hexagonal structure. The degree of ordering of Si depends on the Si/P ratio, while it is independent of the Mn/Fe ratio. The ferromagnetic-paramagnetic magnetoelastic transition is closely related to the size of the magnetic...

Self healing by Cu precipitation in deformed Fe-Cu-B-N-C

Steels are among the most widely used construction materials as their mechanical properties can be tuned over a very wide range of desired combinations of strength formability and other properties. However, when exposed for long times to high temperatures steel components can exhibit premature and low-ductility creep fracture, which arises from...

Effect of carbon on copper precipitation in deformed Fe-based alloys studied by positron annihilation spectroscopy

The role of deformation-induced defects and carbon addition on the copper precipitation during aging at 550 oC is investigated in high-purity Fe-Cu-B-N-C alloy samples by Coincidence Doppler Broadening. In samples with 0% and 8% cold pre-strain, the influence of tensile pre-deformation on the precipitation kinetics of copper is studied. The...

High/low-moment phase transition in hexagonal Mn-Fe-P-Si compounds

Using high-resolution neutron diffraction measurements for Mn-rich hexagonal Mn-Fe-P-Si compounds, we show that the substitution of Mn for Fe on the 3f sites results in a linear decrease of the Fe/Mn(3f) magnetic moments, while the Mn(3g) magnetic moments remain constant. With increasing temperature, the Mn(3g) magnetic moments show almost no...

From first-order magneto-elastic to magneto-structural transition in (Mn,Fe)1.95P0.50Si0.50 compounds

We report on structural, magnetic, and magnetocaloric properties of MnxFe1.95?xP0.50Si0.50 (x???1.10) compounds. With increasing the Mn:Fe ratio, a first-order magneto-elastic transition gradually changes into a first-order magneto-structural transition via a second-order magnetic transition. The study also shows that thermal hysteresis can be...

Giant magnetocaloric effects by tailoring the phase transitions

The MnCoGe alloy can crystallize in either the hexagonal Ni2In- or the orthorhombic TiNiSi-type of structure. In both phases MnCoGe behaves like a typical ferromagnet with a second-order magnetic phase transition. For MnCoGeBx with B on interstitial positions, we discover a giant magnetocaloric effect associated with a single first-order...

From single- to double-first-order magnetic phase transition in magnetocaloric Mn1−xCrxCoGe compounds

Substitution of some Cr for Mn atoms in MnCoGe was employed to control the magnetic and structural transitions in this alloy to coincide, leading to a single first-order magnetostructural transition from the ferromagnetic to the paramagnetic state with a giant magnetocaloric effect observed near room temperature. Further increase in the Cr...

Magnetic properties of Dy nanoparticles and Al2O3-coated Dy nanocapsules