Comparisons of particles thermal behavior between Fe-base alloy and boron carbide during plasma transferred-arc powder surfacing

Comparisons of particle’s thermal behavior between Fe base alloy and boron carbide in plasma transferred arc (PTA) space was made based on theoretical evaluation results in this article. It was found that most of the Fe base particles would be fully melted while they transporting through the central plasma field with 200 A surfacing currents. And the particles with a diameter less than 0.5×10 -4 m might be fully evaporated. However, for the boron carbide (B 4C) particles, only the one with a diameter less than 0.5×10 -4 m could be melted in the same PTA space. Most of B 4C particles are only preheated at its solid state when they were fed through the central field of PTA plasma when the surfacing current is equal to or less than 200 A . When the arc current was smaller than100 A , only the particles smaller than 0.5×10 -4 m could be melted in the PTA space for the Fe base alloy. Almost none of the discussed B 4C particles could be melted in the 100 A PTA space.

Hydrogen Permeation Behavior in Fe_3Al-Based Alloy

Ultra high vacuum gaseous hydrogen permeation experiments on Fe 3Al based alloy were performed in the temperature range of 330～450℃ with an upstream hydrogen pressure between 3.38×10 4 Pa and 7.28×10 4 Pa. The results show that the hydrogen diffusivity and permeability in Fe 3Al based alloy obey Arrhenius relationship in the experimental temperature range and the hydrogen permeation process is controlled by the lattice diffusion of hydrogen at relative high temperature. The activation energy of hydrogen diffusion in the Fe 3Al based alloy was found to be 75 kJ/mol.

EXPLOITATION AND APPLICATIONS OF METASTABLE AUSTENITE MATRIX WEAR ALLOYS

Fe based cast alloys with double phases structure of m etastable austenite m atrix an d eutecticcarbide M7 C3 were provided with the excellent properties of high abrasion resistance andhigher i m pact toughness . An i m portant reason of high abrasion resistance is hard ness violentincreasing on the m atrix surface because of w ear easily induced m artensite transfor m ation . The exploitation and applications of m etastable austenite m atrix wear alloys of Fe C Cr Nisyste m and Fe C Cr Mn system were described in this paper . The excellent properties of thesealloys w ill be sufficiently indicated by authors’exa m ples . To exploit a class of these alloyswith high abrasion resistance and various im pact toughness for m eeting the requirem ent of dif ferent environ ment , the proble m of the structure design of metastable austenite m atrix wearalloy w as also described in this paper .

Amorphous FeNiCoCuSiBCr Alloys with Superior Direct Current Tolerant Characteristics

Amorphous Fe62-x Ni19CoxCu0.1 Si3.8B14Cr1. 1 （x=0, 1, 5, 10） ribbons were annealed under magnetic field and tensile stress, respectively, and their magnetic properties were investigated. Fe73.5 Cu1 Nb3 Si15.5 B7 and Fe66 Ni10- Cu1 Nb3Si11 B9 nanocrystalline alloy ribbons were also fabricated for comparison. Excellent DC tolerant property was obtained in the amorphous FeNiCoCuSiBCr ribbons after thermomagnetic treatment and the constant permeable property was improved with increasing Co content. The relative permeability was constant up to the DC bias field of approximately 6 ×10 ^-4 , 9 ×10 ^-4, and 10 × 10^-4 T and the values of relative permeability μ were 1 650, 1 200, and 1 000 with the Co content being 0, 5 at. %, and 10 at.%, respectively. Besides, stress-annealed FeNiCoCuSiBCr al- loy ribbons were proved to exhibit positive saturation magnetostriction constant λs.