Diffraction & X-Ray Excitation

Appendix

15.1.1 People

Since this is such a young field we decided not to highlight any particular historical characters.

15.1.2 Questions on Analyzing Data

The questions for this chapter are all in the form of exercises. The references for each question are listed on the book’s website.

Q15.1:

Shindo et al. (1986) reported the following X-ray counts from an ALCHEMI experiment in Ti₄₃Al₅₅ Nb₂ using the {110} systematic row. What can you deduce about the Nb occupancy of the two sublattices (Al : A; T i: B)?

Ti43Al55Nb2	s < 0	s > 0	kin	R −/∞	R +/∞
Al K	54 154	51 713	47 139	1.149	1.097
Ti K	112 471	55 584	61 924	1.816	0.898
Nb L	6702	3275	3800	1.764	0.862
Ti/Al	2.080	1.070	1.310
Nb/Al	0.124	0.063	0.081
Nb/Ti	0.060	0.059	0.061

Q15.2:

Miyazaki et al. (1994) reported the following ALCHEMI data for 3 Ni₃Al-Re alloys (110 systematic row). What can you conclude?

Ni75Al23Re2	s < 0	s > 0	kin	R −/∞	R +/∞
Al K	50 000	50 000	50 000	1.000	1.000
Ni K	346 577	302 348	338 567	1.024	0.893
Re M	4874	4471	4668	1.044	0.958
Ni/Al	6.93	6.05	6.77
Re/Al	0.097	0.089	0.093
Re/Ti	0.014	0.015	0.014

Ni74Al24Re2	s < 0	s > 0	kin	R −/∞	R +/∞
Al K	50 000	50 000	50 000	1.000	1.000
Ni K	386 035	317 837	347 658	1.110	0.914
Re M	1955	2071	1994	0.980	1.039
Ni/Al	7.72	6.36	6.95
Re/Al	0.039	0.041	0.040
Re/Ti	0.005	0.007	0.006

Ni73Al25Re2	s < 0	s > 0	kin	R −/∞	R +/∞
Al K	50 000	50 000	50 000	1.000	1.000
Ni K	353 685	279 999	267 209	1.324	1.048
Re M	4084	3977	4090	0.999	0.972
Ni/Al	7.07	5.60	5.34
Re/Al	0.082	0.079	0.082
Re/Ti	0.012	0.014	0.015

Q15.3:

The following intensity data from an ALCHEMI experiment on Ti_47.5Al_47.5Mn₅ were reported by Holmestad et al. (1995). A 001 systematic row was used. Where are the Mn atoms?

Ti47.5Al47.5Mn5	s < 0	s > 0	kin	R −/∞	R +/∞
Al K	475.9	461.7	667.3	0.713	0.692
Ti K	1261.4	960.4	1834.1	0.688	0.524
Mn K	132.6	116.0	184.3	0.719	0.629
Ti/Al	2.65	2.08	2.75
Mn/Al	0.279	0.251	0.276
Mn/Ti	0.105	0.121	0.100

Q15.4:

Nakata et al. (1991) reported the following X-ray data collected during an ALCHEMI experiment using a {100} systematic row in B2 Ti_48.5Ni_48.5Co₃. What can you deduce?

Ti48.5Ni48.5 Co3	s < 0	s > 0	kin	R −/∞	R +/∞
Ti K	53 993	50 803	53 086	1.017	0.957
Ni K	44 698	56 126	54 676	0.818	1.027
Co K	3303	4192	4036	0.818	1.039
Ni/Ti	0.828	1.105	1.030
Co/Ti	0.061	0.083	0.076
Co/Ni	0.074	0.075	0.074

Q15.5:

Gu et al. (1997) report the following for a {110} row in Ni_73.9Al_25.4Zr_0.7. Comment on these results.

	s < 0	s > 0
Al/Ni	0.273	0.179
Zr/Al	0.883	0.877
Zr/Ni	0.241	0.157

Q15.6:

The following table shows some of the results reported by Horita et al. (1995). Where does the Ta sit?

Ni75Al21Ta4	s < 0	s > 0	kin	R −/∞	R +/∞
Al K	15 590	14 060	15 201	1.026	0.925
Ni K	161 533	130 984	149 790	1.233	0.874
Ta M	10 840	9742	10 706	1.013	0.910
Ni/Al	10.4	9.3	9.9
Ta/Al	0.70	0.69	0.70
Ta/Ni	0.067	0.074	0.071

Q15.7:

The same group as in Q15.6 (but a different paper by Horita et al. (1997)) reported some axial channeling ALCHEMI results on the same alloy. What is the answer now?

Ni75Al21Ta4	Axial	kin	R ax/∞
Al K	2020	1746	1.157
Ni K	15 282	8843	1.728
Ta L	814	631	1.290
Ni/Al	7.57	5.06
Ta/Al	0.403	0.361
Ta/Ni	0.053	0.071

Q15.8:

Chen et al. (1990) reported the following NiK/AlK X-ray intensity ratios for Ni₃Al. What do you deduce?

	s < 0	kin
110	7.4	5.2
111	6.1

Q15.9:

Leonard et al. (2000) reported the following X-ray intensity ratios for the Nb₅₀Ti₂₅Al₂₅ {100} B2 systematic row. What are the chemical compositions of the two sublattices?

Nb50Ti25Al25	s < 0	s > 0	kin
Al K/Nb L	0.288	0.427	0.384
Ti K/Nb L	0.625	0.515	0.585
Al K/Ti K	0.460	0.829	0.656

Q15.10:

Analyzing the B2 alloy Ti₄₇V₃₀Cr₁₄Al₁₀, Li et al. (1998) made the following ALCHEMI measurements. What can you say about the compositions of the two sublattices?

Ti47V30Cr14Al10	s < 0	s > 0	kin
Cr/Ti	0.282	0.283	0.268
Al/Ti	0.079	0.101	0.095
V/Ti	0.568	0.682	0.645
Al/V	0.140	0.148	0.147
Cr/V	0.496	0.414	0.416