Nd and reciprocating extrusion of Al_2O_ (3f) / AZ91D composites and high temperature creep

Title: Nd and reciprocating extrusion of Al_2O_ (3f) / AZ91D composites and high temperature creep behavior of Author: Mr Tung Chi-Joe Degree-granting units: Xi'an University of Technology Keywords: Al_2O_ (3f) / AZ91D composite materials;; microstructure;; Nd;; reciprocating extrusion;; high temperature creep Summary: In this paper, prepared by pressureless infiltration of Nd content of 0.0%, 0.2%, 0.5% and 0.8% of the Al2O3f/AZ91D composite (fiber volume fraction of 20%), and different Nd content of the composite materials were reciprocating extrusion. The use of OM (optical microscope), SEM (scanning electron microscopy), XRD (X-ray diffraction) and EDS (EDS) analysis and other detection methods, explore Nd and reciprocating extrusion of composite Neodymium Magnets microstructure, phase composition, hardness and high temperature creep properties. High temperature compression as a means to carry out Al2O3f/AZ91D high temperature creep properties of composite materials research, composite materials, creep through the curve and the creep stress index composite materials, and explore its mechanism of creep and creep process and to explore the high-temperature compression creep change the course of the evolution of microstructure and composite materials dynamic recrystallization mechanism. After the composite materials of Nd added to form a granular and rod-shaped Al-Nd phase, while Nd refine the matrix organization, and tend to make small dispersed Mg2Si phase; of Nd addition can significantly improve the hardness and high temperature composite materials creep, adding 0.8% Nd of Al2O3f/AZ91D composite hardness and resistance to high temperature creep properties of the best; added after the Mg2Si phase Nd hardness then decreased, the Nd content of 0.5% of maximum hardness. Al2O3f/AZ91D composite materials after two times of reciprocating extrusion, a significant refinement of the matrix organization, squeezed to eliminate the fiber segregation, improved fiber distribution; constant temperature (250 ℃) constant load (90MPa), the reciprocating extrusion pressure-state-cast composite materials than the high-temperature creep properties of composite materials has declined; reciprocating extrusion process reduces the hardness http://www.everbeenmagnet.com/en/products/110-sintered-neodymium-magnets of Mg2Si phase, but the hardness of composite materials has improved. After high temperature compression creep of fiber is more evenly distributed, and organizations to further refinement, the matrix deformation twins can be observed and cross-slip line, fiber segregation in the district the formation of recrystallized grains. Composite materials by studying Al2O3f/AZ91D 250 ℃ when the lnε-lnσ curve and fitting a straight line to get the stress exponent n is 6.6, the creep of composite materials by the lattice diffusion controlled dislocation creep model mechanism and sub-structure constant result of the role. According to the n-value mapping (εn-σ) / 1 curve, the composite material at 250 ℃ threshold stress is 1.32MPa. Degree Year: 2010