Influence of microstructure and processing on mechanical properties of advanced Nb-silicide alloys

2012 ◽  
Vol 1516 ◽  
pp. 317-322 ◽  
Author(s):  
C. Seemüller ◽  
M. Heilmaier ◽  
T. Hartwig ◽  
M. Mulser ◽  
N. Adkins ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Fine Particles ◽  
Phase Distribution ◽  
High Energy ◽  
Powder Injection ◽  
Gas Atomization ◽  
Alloyed Powder ◽  
Mechanically Alloyed ◽  
Metallurgical Processing ◽  
Formation Phase

ABSTRACTIn this study different powder metallurgical processing routes, commonly used for refractory metal based materials, were evaluated on their impact on mechanical properties of a multi-component Nb-20Si-23Ti-6Al-3Cr-4Hf (at.%) alloy. Powder was produced by gas-atomization or high energy mechanical alloying of elemental powders and then consolidated either by HIPing or powder injection molding (PIM). The PIM process requires fine particles. In this investigation powder batches of gas-atomized powder (< 25 μm) and mechanically alloyed powder (< 25 μm) were compacted via PIM. Fine (< 25 μm) and coarser (106-225 μm) particle fractions of gas-atomized powder were compacted via HIPing for comparison. Quantitative analysis of the resulting microstructures regarding porosity, phase formation, phase distribution, and grain size was carried out in order to correlate them with the ensuing mechanical properties such as compressive strength at various temperatures.

Effect of Small Iron, Chromium and Boron Additions as Alloying Elements on Microstructure and Mechanical Properties of Ni3Al

2007 ◽  
Vol 23 ◽  
pp. 123-126
Author(s):  
Radu L. Orban ◽  
Mariana Lucaci
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Room Temperature ◽  
Alloying Elements ◽  
Alloyed Powder ◽  
Mechanically Alloyed ◽  
Powder Mixtures ◽  
B Additions ◽  
Strength And Ductility ◽  
Iron Chromium

This paper investigates the effect of Fe, Cr and B additions, in small proportions, as alloying elements in Ni3Al with the purpose to reduce its intrinsic fragility and extrinsic embrittlement and to enhance, in the same time, its mechanical properties. It represents a development of some previous research works of the authors, proving that Ni3Al-Fe-Cr-B alloys obtained by reactive synthesis (SHS) starting from Mechanically Alloyed powder mixtures have superior both room temperature tensile strength and ductility, and compression ones at temperatures up to 800 °C, than pure Ni3Al. These create premises for their using as superalloys substitutes.

Modification of Low Alloyed Steels by Manganese Additions

2007 ◽  
Vol 534-536 ◽  
pp. 697-700 ◽  
Author(s):  
J. Sicre-Artalejo ◽  
Mónica Campos ◽  
Teodora Marcu ◽  
José M. Torralba
Keyword(s):  
Mechanical Properties ◽  
Master Alloy ◽  
Oxygen Affinity ◽  
High Energy ◽  
Alloying Elements ◽  
Sintering Behavior ◽  
Mechanically Alloyed ◽  
Prealloyed Powder ◽  
High Oxygen Affinity ◽  
The Cost

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.

Rapid Consolidation of Nanocrystalline Al2O3 Reinforced Cr Composite from Mechanically Alloyed Powders by Pulsed Current Activated Sintering

2010 ◽  
Vol 123-125 ◽  
pp. 197-200 ◽  
Author(s):  
In Jin Shon ◽  
Hyun Su Kang ◽  
Dong Mok Lee ◽  
Kwon Il Na ◽  
In Yong Ko
Keyword(s):  
Mechanical Properties ◽  
Grain Size ◽  
High Energy ◽  
Pulsed Current ◽  
Mechanically Alloyed ◽  
Activated Sintering ◽  
Simultaneous Application ◽  
Al2o3 Composite ◽  
Average Grain Size ◽  
Energy Ball

Nanopowders of Cr and Al2O3 was fabricated from CrO3 and 2Al by high energy ball milling. Dense nanocrystalline Cr-Al2O3 composite was consolidated by pulsed current activated sintering (PCAS) method within 1 min from mechanically alloyed powders. Highly dense Cr-Al2O3 with relative density of up to 99% was produced under simultaneous application of a 80 MPa pressure and the pulsed current. The average grain size and mechanical properties of the composite were investigated.

Effect of Aluminum on Fabrication of Ti3SiC2 by Mechanical Alloying and Spark Plasma Sintering

2007 ◽  
Vol 336-338 ◽  
pp. 1065-1068
Author(s):  
Song Zhe Jin ◽  
Bao Yan Liang ◽  
Jing Feng Li ◽  
Li Li
Keyword(s):  
Mechanical Alloying ◽  
Spark Plasma Sintering ◽  
High Purity ◽  
Trace Amount ◽  
High Energy ◽  
Alloyed Powder ◽  
Mechanically Alloyed ◽  
Starting Mixture ◽  
Plasma Sintering ◽  
Spark Plasma

In the present study, we fabricated high purity and electrically machinable Ti3SiC2 ceramics by mechanical alloying and subsequent spark plasma sintering. The effect of a trace amount of Al on these synthesis processes was examined. Our results showed that Ti3SiC2 could be synthesized by high energy milling. Spark plasma sintering of mechanically alloyed powder at the temperatures of 1000-1200°C produced nearly single-phased Ti3SiC2 materials. The purity of the sintered Ti3SiC2 bulk was remarkably increased by addition of a small amount of Al. Ti3SiC2 with a purity of 99.3 wt% and a relative density of 98.9% was obtained by mechanical alloying and subsequent spark plasma sintering from a starting mixture composed of n(Ti) : n(Si) : n(Al) : n(c) = 3 : 1 : 0.2 : 2 at 1100°C.

Sintering Behavior of Si3N4-TaC Based Composites

2005 ◽  
Vol 498-499 ◽  
pp. 357-362
Author(s):  
Ana Carolina S. Coutinho Rumbao ◽  
José Carlos Bressiani ◽  
Ana Helena A. Bressiani
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Silicon Nitride ◽  
Phase Distribution ◽  
Particulate Composite ◽  
High Energy ◽  
Thermomechanical Properties ◽  
Sintering Behavior ◽  
High Temperature Strength ◽  
Kinetics Of

Silicon nitride was the first nitride developed for engineering applications. The excellent combination of thermomechanical properties makes silicon nitride a good candidate for applications where high hardness and mechanical properties are fundamental. However, the low fracture toughness of this material limits its use as structural material. The improve of mechanical properties of silicon nitride comes from many factors, like refined microstructure by restraining grain growth, localized stress, crack tip bridging, etc. Within these factors, microstructure formation of the silicon nitride is critically important for the final properties. The design of silicon nitride based composite materials is of particular interest because of their improved high temperature strength and fracture toughness. In this work, Si3N4-TaC particulate composite was investigated. For this study was prepared a basis composition (CB) with 90%wt a-Si3N4, 6%wt and 4%wt Y2O3 and Al2O3, respectively. TaC (20%vol) was added into CB and after mixture, in high-energy milling, the powder was compacted into pellets. The kinetics of sintering was studied by means of dilatometry. The shrinkage rate versus time and temperature curves exhibit two well-defined peaks. The first peak refers to the particle rearrangement process and the second, more pronounced, to solutionreprecipitation process. It is quite clear that the presence of TaC particles has small influence on sintering kinetics of silicon nitride. It was observed the complete a®b-Si3N4 phase transformation. The microstructure shows good homogeneity both in regard of grain size and secondary phase distribution.

Mechanical Milling of Prealloyed Cu-Cr Powders Prepared by Gas Atomization

2007 ◽  
Vol 26-28 ◽  
pp. 469-472 ◽  
Author(s):  
Hwan Kyun Yeo ◽  
Sang Ho Ahn ◽  
Kwan Hee Han
Keyword(s):  
Stainless Steel ◽  
Milled Powder ◽  
High Energy ◽  
Gas Atomization ◽  
Mechanically Alloyed ◽  
Attrition Milling ◽  
Nano Crystalline ◽  
State Regime ◽  
Small Grains ◽  
Steel Balls

In this study, we investigate the effects of high energy milling under Ar atmosphere on the morphology, size and microstructure of Cu-Cr alloy powders prepared by gas atomization. The attrition milling using stainless steel balls is performed up to 60 hrs. The observation by SEM and TEM shows apparent sequential changes of morphology and size of powders similar to those that are typical for mechanically alloyed elemental powders. Prolonged milling in the steady state regime produces a nano-crystalline structure, consisting of extremely small grains of 20 to 50 nm in size and finely dispersed Cr particles. It is also shown that the uptake of Fe from the stainless steel balls and vessel is appreciable. The microhardness of milled powder increases with the milling time, reaches its peak and then slightly decreases.

Synthesis and Mechanical Properties of Nano-Scale NiAl and NiAl/Al2O3 Composites

1994 ◽  
Vol 350 ◽  
Author(s):  
Timothy R. Smith
Keyword(s):  
Mechanical Properties ◽  
Composite Materials ◽  
High Energy ◽  
Alloyed Powder ◽  
High Energy Milling ◽  
Nano Scale ◽  
Sinter Forging

AbstractThis work reports on the synthesis, characterization and preliminary mechanical properties of nanocrystalline NiAl/Al2O3 composite materials. Nano-scale crystallites of NiAl were formed by high energy milling of pre-alloyed powder with and without Al2O3 under an Ar atmosphere. Consolidation of the nano-scale powders was done by sinter-forging at < 0.4 Tm in air. Characterization of the powders and consolidated microstructures and hardness data are reported.

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