Preparation of High-TcCeramic Superconductors Through Oxidation of Mechanically Alloyed Master Alloy Powders

The efforts to increase the potential PM market [makes necessary to accept new challenges to develop new products. To address this question, we can consider modifying the pores system or the material composition and at same time, the cost of the alloying elements and the compromise between strength, tolerances and cost. The present study examines the sintering behavior and effect of manganese addition, both mechanically-blended and mechanically alloyed, on Cr-Mo low alloyed steels to enhance the mechanical properties. Mn sublimation during sintering results in some specific phenomena to occur which facilitate the sintering of alloying elements with high oxygen affinity. To benefit from the Mn sublimation effects, small Mn particles must be homogenously added in order to increase the specific surface available to sublimate. First, the milling time is optimized to attain a master alloy with 50% of Mn that is diluted in Fe-1.5Cr-0.2Mo water atomized prealloyed powder by normal mixing. These mixtures were pressed to a green density of 7.1 g/cm3 and sintered at 1120 °C in 90N2-10H2 atmosphere. The resulting mechanical properties and the microstructures are discussed considering the high energy stored in the master alloy which favors the mass transport mechanism during sintering.

Download Full-text

Fine Microstructure of a Mechanically Alloyed Oxide Dispersion Strengthened Nickel-Base Superalloy

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100079012 ◽

1977 ◽

Vol 35 ◽

pp. 298-299

Author(s):

Jordi Marti ◽

Timothy E. Howson ◽

David Kratz ◽

John K. Tien

Keyword(s):

Solid Solution ◽

Volume Fraction ◽

Stress Rupture ◽

Oxide Dispersion Strengthened ◽

Solid Solution Alloy ◽

Oxide Dispersion ◽

Creep And Stress Rupture ◽

Mechanically Alloyed ◽

Fine Microstructure ◽

Nickel Base

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.

Download Full-text

Microstructure of mechanically alloyed and hot-pressed Al5CuZr2

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100177982 ◽

1990 ◽

Vol 48 (4) ◽

pp. 970-971

Author(s):

T. E. Mitchell ◽

P. B. Desch ◽

R. B. Schwarz

Keyword(s):

Mechanical Alloying ◽

Vickers Hardness ◽

Hot Pressing ◽

Rapid Quenching ◽

Hardened Steel ◽

Alloyed Powder ◽

Ion Milling ◽

Mechanical Grinding ◽

Mechanically Alloyed ◽

Steel Container

Al3Zr has the highest melting temperature (1580°C) among the tri-aluminide intermetal1ics. When prepared by casting, Al3Zr forms in the tetragonal DO23 structure but by rapid quenching or by mechanical alloying (MA) it can also be prepared in the metastable cubic L12 structure. The L12 structure can be stabilized to at least 1300°C by the addition of copper and other elements. We report a TEM study of the microstructure of bulk Al5CuZr2 prepared by hot pressing mechanically alloyed powder.MA was performed in a Spex 800 mixer using a hardened steel container and balls and adding hexane as a surfactant. Between 1.4 and 2.4 wt.% of the hexane decomposed during MA and was incorporated into the alloy. The mechanically alloyed powders were degassed in vacuum at 900°C. They were compacted in a ram press at 900°C into fully dense samples having Vickers hardness of 1025. TEM specimens were prepared by mechanical grinding followed by ion milling at 120 K. TEM was performed on a Philips CM30 at 300kV.

Download Full-text

Processing and characterization of mechanically alloyed immiscible metals

International Journal of Materials Research (formerly Zeitschrift fuer Metallkunde) ◽

10.3139/146.110781 ◽

2012 ◽

Vol 103 (9) ◽

pp. 1125-1129 ◽

Cited By ~ 9

Author(s):

Challapalli Suryanarayana ◽

Jinling Liu

Keyword(s):

Mechanically Alloyed

Download Full-text

Structural Studies of Mechanically Alloyed Fe1–xAlx Powder

Journal of Nano- and Electronic Physics ◽

10.21272/jnep.12(4).04012 ◽

2020 ◽

Vol 12 (4) ◽

pp. 04012-1-04012-5

Author(s):

S. Khan ◽

◽

A. Vyas ◽

S. Rajan ◽

S. Jani ◽

...

Keyword(s):

Structural Studies ◽

Mechanically Alloyed

Download Full-text

The influence of gadolinium on Al–Ti–C master alloy and its refining effect on AZ31 magnesium alloy

International Journal of Materials Research (formerly Zeitschrift fuer Metallkunde) ◽

10.1515/ijmr-2020-7779 ◽

2021 ◽

Vol 0 (0) ◽

Author(s):

Wenxue Fan ◽

Hai Hao

Keyword(s):

Mechanical Properties ◽

Magnesium Alloy ◽

Grain Refinement ◽

Magnesium Alloys ◽

Master Alloy ◽

Cast Alloy ◽

Az31 Magnesium Alloy ◽

Synthesis Mechanism ◽

Refining Effect ◽

Master Alloys

Abstract Grain refinement has a significant influence on the improvement of mechanical properties of magnesium alloys. In this study, a series of Al–Ti–C-xGd (x = 0, 1, 2, 3) master alloys as grain refiners were prepared by self-propagating high-temperature synthesis. The synthesis mechanism of the Al–Ti–C-xGd master alloy was analyzed. The effects of Al–Ti–C-xGd master alloys on the grain refinement and mechanical properties of AZ31 (Mg-3Al-1Zn-0.4Mn) magnesium alloys were investigated. The results show that the microstructure of the Al–Ti–C-xGd alloy contains α-Al, TiAl3, TiC and the core–shell structure TiAl3/Ti2Al20Gd. The refining effect of the prepared Al–Ti–C–Gd master alloy is obviously better than that of Al–Ti–C master alloy. The grain size of AZ31 magnesium alloy was reduced from 323 μm to 72 μm when adding 1 wt.% Al–Ti–C-2Gd master alloy. In the same condition, the ultimate tensile strength and elongation of as-cast alloy were increased from 130 MPa, 7.9% to 207 MPa, 16.6% respectively.

Download Full-text