# Prediction and characterization of variant electron diffraction patterns for {gamma}{double_prime} and {delta} precipitates in an Inconel 718 alloy

## Abstract

A universal theoretical method has been developed in this article to predict and characterize electron diffraction patterns (EDPs) which contain various variants of precipitate(s) with a matrix. The plane and direction transition matrices for three {gamma}{double_prime}-phase variants and 12 {delta}-phase variants precipitated from a {gamma} matrix in the Inconel 718 alloy were deduced, from which the EDPs for seven low-index zones of {gamma} matrix containing {gamma}{double_prime} precipitates were predicted by plotting and were found to be consistent with transmission electron microscopy (TEM) observations, showing that some of the results reported by Quist et al. should be corrected. Meanwhile, three variants of {delta} phase, precipitated from any one of four {l_brace}111{r_brace} matrices in 12 possible orientational variants, were also predicted and confirmed by EDPs. Different from Paulonis` conclusion, the theoretical calculations indicated that the {l_brace}1/2 1 0{r_brace}-type superlattice reflections in the <100> zone of the {gamma} matrix permitted detection of both {gamma}{double_prime}- and {sigma}-phase precipitates, but not of {gamma}{double_prime}-phase precipitates. Therefore, the precipitates shown in dark-field images using these superlattice reflections cannot be unambiguously determined to be {gamma}{double_prime} phase. A unique approach for identification of {gamma}{double_prime} precipitates in the alloy has been proposed.

- Authors:

- Shanghai Jiao Tong Univ. (China). School of Materials Science and Engineering
- Lehigh Univ., Bethlehem, PA (United States). Dept. of Mechanical Engineering and Mechanics

- Publication Date:

- Sponsoring Org.:
- USDOE

- OSTI Identifier:
- 684449

- Resource Type:
- Journal Article

- Journal Name:
- Metallurgical and Materials Transactions. A, Physical Metallurgy and Materials Science

- Additional Journal Information:
- Journal Volume: 30; Journal Issue: 9; Other Information: PBD: Sep 1999

- Country of Publication:
- United States

- Language:
- English

- Subject:
- 36 MATERIALS SCIENCE; MICROSTRUCTURE; INCONEL 718; PRECIPITATION; INTERMETALLIC COMPOUNDS; ELECTRON DIFFRACTION

### Citation Formats

```
Rong, Y., Chen, S., Hu, G., Gao, M., and Wei, R.P.
```*Prediction and characterization of variant electron diffraction patterns for {gamma}{double_prime} and {delta} precipitates in an Inconel 718 alloy*. United States: N. p., 1999.
Web. doi:10.1007/s11661-999-0239-x.

```
Rong, Y., Chen, S., Hu, G., Gao, M., & Wei, R.P.
```*Prediction and characterization of variant electron diffraction patterns for {gamma}{double_prime} and {delta} precipitates in an Inconel 718 alloy*. United States. doi:10.1007/s11661-999-0239-x.

```
Rong, Y., Chen, S., Hu, G., Gao, M., and Wei, R.P. Wed .
"Prediction and characterization of variant electron diffraction patterns for {gamma}{double_prime} and {delta} precipitates in an Inconel 718 alloy". United States. doi:10.1007/s11661-999-0239-x.
```

```
@article{osti_684449,
```

title = {Prediction and characterization of variant electron diffraction patterns for {gamma}{double_prime} and {delta} precipitates in an Inconel 718 alloy},

author = {Rong, Y. and Chen, S. and Hu, G. and Gao, M. and Wei, R.P.},

abstractNote = {A universal theoretical method has been developed in this article to predict and characterize electron diffraction patterns (EDPs) which contain various variants of precipitate(s) with a matrix. The plane and direction transition matrices for three {gamma}{double_prime}-phase variants and 12 {delta}-phase variants precipitated from a {gamma} matrix in the Inconel 718 alloy were deduced, from which the EDPs for seven low-index zones of {gamma} matrix containing {gamma}{double_prime} precipitates were predicted by plotting and were found to be consistent with transmission electron microscopy (TEM) observations, showing that some of the results reported by Quist et al. should be corrected. Meanwhile, three variants of {delta} phase, precipitated from any one of four {l_brace}111{r_brace} matrices in 12 possible orientational variants, were also predicted and confirmed by EDPs. Different from Paulonis` conclusion, the theoretical calculations indicated that the {l_brace}1/2 1 0{r_brace}-type superlattice reflections in the <100> zone of the {gamma} matrix permitted detection of both {gamma}{double_prime}- and {sigma}-phase precipitates, but not of {gamma}{double_prime}-phase precipitates. Therefore, the precipitates shown in dark-field images using these superlattice reflections cannot be unambiguously determined to be {gamma}{double_prime} phase. A unique approach for identification of {gamma}{double_prime} precipitates in the alloy has been proposed.},

doi = {10.1007/s11661-999-0239-x},

journal = {Metallurgical and Materials Transactions. A, Physical Metallurgy and Materials Science},

number = 9,

volume = 30,

place = {United States},

year = {1999},

month = {9}

}