scholarly journals Production of Oxide Dispersion Strengthened Mg-Zn-Y Alloy by Equal Channel Angular Pressing of Mechanically Alloyed Powder

Metals ◽  
2020 ◽  
Vol 10 (5) ◽  
pp. 679 ◽  
Author(s):  
Keng-Liang Ou ◽  
Chia-Chun Chen ◽  
Chun Chiu

Mg-Zn-Y alloys with long-period stacking ordered structures (LPSO) have attracted attention due to their excellent mechanical properties. In addition to the LPSO structure, Mg alloys can also be strengthened by oxide particles. In the present study, oxide dispersion strengthened Mg97Zn1Y2 (at%) alloys were prepared by equal channel angular pressing (ECAP) of mechanical alloyed (MA) powder under an oxygen gas atmosphere. The 20-h-MA powder had a particle size of 28 μm and a crystallite size of 36 nm. During the MA process followed by ECAP, an Mg matrix with dispersed Y2O3 (and MgO) particles was formed. The alloy processed by ECAP exhibited a hardness of 110 HV and a compressive strength of 185 MPa. Compared to pure Mg, the increased hardness was due to the dispersion strengthening of Y2O3 and MgO particles and solution strengthening of Zn and Y.

Author(s):  
Jordi Marti ◽  
John E. Stulga ◽  
John K. Tien

A recent development in powder metallurgy technology, known as mechanical alloying (1), can find applications in alloys which cannot be manufactured by conventional processes, due to high melting temperatures, chemical incompatibility of constituents in the melt, or high reactivity. The process has been utilized in the production of a nickel-base superalloy and a nickel-base solid solution which contain dispersions of fine and inert oxide particles for high temperature strength. As part of a study of the creep and stress rupture behavior of these alloys, the as-received and crept microstructures have been examined using the transmission electron microscope. This note discusses the fine-scale microstructure of the mechanically alloyed oxide dispersion strengthened (ODS) nickel-base solid solution.The alloy has a nominal chemical composition in weight percent of Ni - 20Cr - 0.5Ti - 0.3A1 with O.6Y2O3 oxide particles.


Author(s):  
Jordi Marti ◽  
Timothy E. Howson ◽  
David Kratz ◽  
John K. Tien

The previous paper briefly described the fine microstructure of a mechanically alloyed oxide dispersion strengthened nickel-base solid solution. This note examines the fine microstructure of another mechanically alloyed system. This alloy differs from the one described previously in that it is more generously endowed with coherent precipitate γ forming elements A1 and Ti and it contains a higher volume fraction of the finely dispersed Y2O3 oxide. An interesting question to answer in the comparative study of the creep and stress rupture of these two ODS systems is the role of the precipitate γ' in the mechanisms of creep and stress rupture in alloys already containing oxide dispersoids.The nominal chemical composition of this alloy is Ni - 20%Cr - 2.5%Ti - 1.5% A1 - 1.3%Y203 by weight. The system receives a three stage heat treatment-- the first designed to produce a coarse grain structure similar to the solid solution alloy but with a smaller grain aspect ratio of about ten.


Metals ◽  
2019 ◽  
Vol 9 (11) ◽  
pp. 1148 ◽  
Author(s):  
Roman Husák ◽  
Hynek Hadraba ◽  
Zdeněk Chlup ◽  
Milan Heczko ◽  
Tomáš Kruml ◽  
...  

Oxide dispersion-strengthened (ODS) materials contain homogeneous dispersions of temperature-stable nano-oxides serving as obstacles for dislocations and further pinning of grain boundaries. The strategy for dispersion strengthening based on complex oxides (Y-Hf, -Zr, -Ce, -La) was developed in order to refine oxide dispersion to enhance the dispersion strengthening effect. In this work, the strengthening of EUROFER steel by complex oxides based on Y and elements of the IIIB group (lanthanum, scandium) and IVB group (cerium, hafnium, zirconium) was explored. Interparticle spacing as a dispersoid characteristic appeared to be an important factor in controlling the dispersion strengthening contribution to the yield strength of ODS EUROFER steels. The dispersoid size and average grain size of ODS EUROFER steel were altered in the ranges of 5–13 nm and 0.6–1.7 µm, respectively. Using this strategy, the yield strength of the prepared alloys varied between 550 MPa and 950 MPa depending on the doping element.


2017 ◽  
Vol 493 ◽  
pp. 180-188 ◽  
Author(s):  
N.H. Oono ◽  
S. Ukai ◽  
S. Hayashi ◽  
S. Ohtsuka ◽  
T. Kaito ◽  
...  

Sign in / Sign up

Export Citation Format

Share Document