Amorphization and disordering of the Ni<sub>3</sub>Al ordered intermetallic by mechanical milling

Jang, J.S.C.; Koch, Carl C.

doi:10.1557/jmr.1990.0498

Cited by 276 publications

(73 citation statements)

References 33 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…As Ni 3 Al is ordered up to the melting point, disordered Ni 3 Al needs to be produced by vapor deposition [29] or ball milling [30]. Both of these methods produce a material with a very small grain size (respectively, 4 nm [29] and 7 nm [31]).…”

mentioning

confidence: 99%

First-Principles Computation of the Vibrational Entropy of Ordered and DisorderedNi3Al

1998

View full text Add to dashboard Cite

There is increasing evidence that vibrational entropy may significantly contribute to the entropy difference between the ordered and the disordered states of a compound. Through first-principles calculations, we investigate the magnitude of this vibrational entropy difference in Ni 3 Al, a compound where this effect is believed to be especially large. We find the vibrational entropy difference to be essentially zero and temperature independent. [S0031-9007(98)06236-X] PACS numbers: 64.70. Kb, 65.50. + m First-principles theory of order-disorder phase equilibria is a well-established field [1,2]. Typically, only configurational entropy is accounted for, and the effect of lattice vibrations on the free energy difference between the ordered and the disordered states is neglected, although no formal justification of this assumption has ever been presented. On the contrary, recent experimental data [3][4][5][6] seem to indicate that, in many systems, the vibrational entropy difference between the ordered and the disordered states is comparable to the configurational entropy difference. An especially striking example is the Ni 3 Al compound, for which the vibrational entropy difference was estimated from experimental observations to be 0.2k B [4], whereas the configurational entropy difference is at most 0.57k B . If this estimate is correct, it may explain why most first-principles calculations including only configurational entropy consistently overestimate phase transition temperatures. Based on the experimental data of Fultz and co-workers [4], Garbulsky [7] predicted that vibrational effects would shift down the calculated order-disorder transition temperature of Ni 3 Al by 18% from what it would be with a configurational-only entropy model.In order to unambiguously confirm that lattice vibrations indeed play an important role, this experimental evidence needs to be backed by a suitable theoretical investigation. Unfortunately, highly accurate first-principles calculations of the vibrational entropy are very computationally intensive tasks. In this context, several investigators turned to simplified models to estimate the vibrational entropy. In some studies [8,9], the complexity of the first-principles approach was tackled by using a simplified model for the vibrational entropy based on the Debye-Gruneisen approximation. All of these results seem to indicate that vibrational effects can be non-negligible.Calculations of the vibrational entropy difference between disordered and ordered Ni 3 Al (hereafter denoted DS o!d vib ) has so far been performed using only the semiempirical embedded atom method (EAM) [10][11][12]. Although the specific result seems to depend somewhat on the EAM potential used, all authors found values between 0.1k B and 0.3k B , which corresponds to the range of values found experimentally.Although the value of DS o!d vib calculated through EAM agrees with experimental results, there is no consensus on the origin of this difference. The EAM results indicate that disordering causes a nearl...

show abstract

mentioning

confidence: 99%

First-Principles Computation of the Vibrational Entropy of Ordered and DisorderedNi3Al

1998

View full text Add to dashboard Cite

show abstract

“…28,29) It has been found that the accumulation of structure defects, such as vacancies, dislocations, grain boundaries and distortion of lattice and the refinement of grain lead to the increase of the Gibbs free energy of crystalline phase. 30,31) If the free energy of crystalline phase is higher than that of the glassy phase, the transformation to the glassy state can be expected.…”

Section: Resultsmentioning

confidence: 99%

Glass Formation in a Ni-Based Multicomponent Alloy by Mechanical Milling and Microwave Treatment of The Obtained Powders

Xie

Louzguine-lugzin

et al. 2009

Mater. Trans.

View full text Add to dashboard Cite

Glass formation was achieved by mechanical milling of crystalline Ni 59 Ti 16 Zr 20 Sn 5 pre-alloyed powders. Compared to the glassy alloy ribbon of the same composition obtained by melting-spinning method, the alloy powders milled for 24 h exhibited a lower crystallization temperature and do not have a distinct glass-transition characteristic. X-ray diffraction (XRD) and transmission electron microscopy (TEM) results indicated that a small fraction of the powder exists in nanocrystalline state within the glassy matrix. The obtained Ni 59 Ti 16 Zr 20 Sn 5 powdered specimen was heated rapidly by microwave radiation and the bulk porous sample was obtained under a low applied pressure of 5 MPa.

show abstract

“…• Contrary, Jang et al [10] observed a complete disordering by ball milling of the ordered Ni3 A1 intermetallic compound which has an L12 (ordered fcc) crystal structure. The value of LRO parameter S decreases monotonically from 1 to O after several hours of processing.…”

Section: Disordering By Mechanical Milling •mentioning

confidence: 94%

Mechanical Alloying - a Novel Method for Synthesis and Processing of Materials

Oleszak

1999

Acta Phys. Pol. A

View full text Add to dashboard Cite

High energy ball milling (mechanical alloying) has recently become a popular research topic. As the non-equilibrium processing method, this technique may be used for the synthesis of many materials, including metastable ones. In many cases these materials exhibit the structure and properties quite different from materials prepared by conventional methods. In this paper some examples of metastable structures synthesized by mechanical alloying are described. The results of mechanical alloying in the Fe-Al system are presented as well.

show abstract

Amorphization and disordering of the Ni₃Al ordered intermetallic by mechanical milling

Cited by 276 publications

References 33 publications

First-Principles Computation of the Vibrational Entropy of Ordered and DisorderedNi3Al

First-Principles Computation of the Vibrational Entropy of Ordered and DisorderedNi3Al

Glass Formation in a Ni-Based Multicomponent Alloy by Mechanical Milling and Microwave Treatment of The Obtained Powders

Mechanical Alloying - a Novel Method for Synthesis and Processing of Materials

Contact Info

Product

Resources

About

Amorphization and disordering of the Ni3Al ordered intermetallic by mechanical milling

Cited by 276 publications

References 33 publications

First-Principles Computation of the Vibrational Entropy of Ordered and DisorderedNi3Al

First-Principles Computation of the Vibrational Entropy of Ordered and DisorderedNi3Al

Glass Formation in a Ni-Based Multicomponent Alloy by Mechanical Milling and Microwave Treatment of The Obtained Powders

Mechanical Alloying - a Novel Method for Synthesis and Processing of Materials

Contact Info

Product

Resources

About

Amorphization and disordering of the Ni₃Al ordered intermetallic by mechanical milling