Ni-Al-Ti: Interdiffusion

Interdiffusion in the Ni-rich part of the Ni-Al-Ti system was studied at 900 to 1200C. Attention was concentrated on the face-centered cubic γ-phase. The diffusivity values (tables 173 and 174) were deduced from concentration profiles which were measured by means of electron probe micro-analysis, using a modified form of the Boltzmann-Matano method. The diffusion couples were of the form: γ/γ, γ/γ’ or γ’/γ’, where γ’ was the L12 phase. The coefficients, DAlAl and DTiTi, were almost equal and varied only slightly with composition. The coefficients, DAlTi and DTiAl, were up to an order of magnitude smaller and exhibited a considerable compositional dependence. When plotted onto the ternary phase diagram, the DAlAl and DAlTi contours lay roughly parallel to the Al iso-concentration lines. The DTiTi and DTiAl contours followed the iso-concentration lines for Ti. The activation energies of all of the coefficients were found to be similar for the present compositions. Observations were made of the accumulation of Kirkendall porosity in the interdiffusion zone, of the locations of the γ/(γ+ γ’) and γ’/(γ+γ') phase boundaries and of their migration rate.

M.S.A.Karunaratne, P.Carter, R.C.Reed: Acta Materialia, 2001, 49[5], 861–75

Table 172

Diffusion Parameters for Self-Diffusion in Ni-Al-Ti Alloys,

as Deduced using Various Techniques and Analyses

Al(at%)	Ti(at%)	Technique	Analysis	o(s)	E(eV)
4	0	both	power law	6.2 x 10-18	2.96
4	0	down-quenching	power law	1.4 x 10-18	3.05
4	0	both	distribution law	3.7 x 10-18	3.00
4	0	down-quenching	distribution law	1.8 x 10-19	3.18
4	2	both	power law	8.8 x 10-15	2.79
4	2	down-quenching	power law	6.6 x 10-20	3.22
4	2	up-quenching	power law	8.5 x 10-15	2.54
4	2	both	distribution law	1.3 x 10-17	2.92
4	2	down-quenching	distribution law	3.0 x 10-21	3.41
4	2	up-quenching	distribution law	1.6 x 10-17	2.95
3	1	both	power law	3.3 x 10-16	2.67
3	1	both	distribution law	1.1 x 10-17	2.61

Table 173

Ternary Interdiffusion Coefficients for the γ-Phase of the Ni-Al-Ti System

Al (wt%)	Ti (wt%)	Temperature (C)	Coefficient	Value (m2/s)
1.41	1.78	900	DAlAlNi	2.50 x 10-16
1.41	1.78	900	DAlTiNi	3.45 x 10-17
1.41	1.78	900	DTiAlNi	1.13 x 10-16
1.41	1.78	900	DTiTiNi	2.85 x 10-16

continued

Table 173 (continued)

Ternary Interdiffusion Coefficients for the γ-Phase of the Ni-Al-Ti System

Al (wt%)	Ti (wt%)	Temperature (C)	Coefficient	Value (m2/s)
1.62	1.40	900	DAlAlNi	2.78 x 10-16
1.62	1.40	900	DAlTiNi	3.25 x 10-17
1.62	1.40	900	DTiAlNi	7.82 x 10-17
1.62	1.40	900	DTiTiNi	2.89 x 10-16
1.90	0.92	900	DAlAlNi	2.89 x 10-16
1.90	0.92	900	DAlTiNi	4.87 x 10-17
1.90	0.92	900	DTiAlNi	8.15 x 10-17
1.90	0.92	900	DTiTiNi	8.90 x 10-17
2.06	2.49	900	DAlAlNi	2.82 x 10-16
2.06	2.49	900	DAlTiNi	3.76 x 10-17
2.06	2.49	900	DTiAlNi	1.23 x 10-16
2.06	2.49	900	DTiTiNi	2.89 x 10-16
2.17	0.44	900	DAlAlNi	2.13 x 10-16
2.17	0.44	900	DAlTiNi	1.71 x 10-17
2.17	0.44	900	DTiAlNi	6.90 x 10-18
2.17	0.44	900	DTiTiNi	2.49 x 10-16
2.38	1.98	900	DAlAlNi	3.43 x 10-16
2.38	1.98	900	DAlTiNi	8.03 x 10-17
2.38	1.98	900	DTiAlNi	8.90 x 10-17
2.38	1.98	900	DTiTiNi	2.69 x 10-16
3.01	1.31	900	DAlAlNi	3.53 x 10-16
3.01	1.31	900	DAlTiNi	1.10 x 10-16
3.01	1.31	900	DTiAlNi	1.13 x 10-16
3.01	1.31	900	DTiTiNi	2.86 x 10-16
3.67	0.72	900	DAlAlNi	3.04 x 10-16
3.67	0.72	900	DAlTiNi	8.10 x 10-17
3.67	0.72	900	DTiAlNi	3.01 x 10-17
3.67	0.72	900	DTiTiNi	2.11 x 10-16

continued

Table 173 (continued)

Ternary Interdiffusion Coefficients for the γ-Phase of the Ni-Al-Ti System

Al (wt%)	Ti (wt%)	Temperature (C)	Coefficient	Value (m2/s)
1.33	1.69	1000	DAlAlNi	2.21 x 10-15
1.33	1.69	1000	DAlTiNi	2.68 x 10-16
1.33	1.69	1000	DTiAlNi	8.67 x 10-16
1.33	1.69	1000	DTiTiNi	2.48 x 10-15
1.53	1.31	1000	DAlAlNi	2.12 x 10-15
1.53	1.31	1000	DAlTiNi	2.38 x 10-16
1.53	1.31	1000	DTiAlNi	6.53 x 10-16
1.53	1.31	1000	DTiTiNi	2.32 x 10-15
1.82	0.91	1000	DAlAlNi	2.14 x 10-15
1.82	0.91	1000	DAlTiNi	3.62 x 10-16
1.82	0.91	1000	DTiAlNi	3.27 x 10-16
1.82	0.91	1000	DTiTiNi	2.28 x 10-15
1.99	2.43	1000	DAlAlNi	2.44 x 10-15
1.99	2.43	1000	DAlTiNi	4.89 x 10-16
1.99	2.43	1000	DTiAlNi	1.04 x 10-15
1.99	2.43	1000	DTiTiNi	2.54 x 10-15
1.99	0.44	1000	DAlAlNi	2.38 x 10-15
1.99	0.44	1000	DAlTiNi	4.26 x 10-16
1.99	0.44	1000	DTiAlNi	3.94 x 10-16
1.99	0.44	1000	DTiTiNi	2.06 x 10-15
2.45	1.94	1000	DAlAlNi	2.43 x 10-15
2.45	1.94	1000	DAlTiNi	2.89 x 10-16
2.45	1.94	1000	DTiAlNi	8.65 x 10-16
2.45	1.94	1000	DTiTiNi	2.40 x 10-15
2.94	1.37	1000	DAlAlNi	2.69 x 10-15
2.94	1.37	1000	DAlTiNi	1.57 x 10-16
2.94	1.37	1000	DTiAlNi	5.74 x 10-16
2.94	1.37	1000	DTiTiNi	2.15 x 10-15

continued

Table 173 (continued)

Ternary Interdiffusion Coefficients for the γ-Phase of the Ni-Al-Ti System

Al (wt%)	Ti (wt%)	Temperature (C)	Coefficient	Value (m2/s)
1.33	1.73	1100	DAlAlNi	1.52 x 10-14
1.33	1.73	1100	DAlTiNi	1.49 x 10-15
1.33	1.73	1100	DTiAlNi	6.12 x 10-15
1.33	1.73	1100	DTiTiNi	1.80 x 10-14
1.52	1.38	1100	DAlAlNi	1.64 x 10-14
1.52	1.38	1100	DAlTiNi	2.07 x 10-15
1.52	1.38	1100	DTiAlNi	5.32 x 10-15
1.52	1.38	1100	DTiTiNi	1.74 x 10-14
1.80	0.87	1100	DAlAlNi	1.63 x 10-14
1.80	0.87	1100	DAlTiNi	1.89 x 10-15
1.80	0.87	1100	DTiAlNi	4.25 x 10-15
1.80	0.87	1100	DTiTiNi	1.59 x 10-14
1.99	2.42	1100	DAlAlNi	1.69 x 10-14
1.99	2.42	1100	DAlTiNi	2.39 x 10-15
1.99	2.42	1100	DTiAlNi	8.27 x 10-15
1.99	2.42	1100	DTiTiNi	1.86 x 10-14
2.03	0.43	1100	DAlAlNi	1.94 x 10-14
2.03	0.43	1100	DAlTiNi	3.48 x 10-15
2.03	0.43	1100	DTiAlNi	2.85 x 10-15
2.03	0.43	1100	DTiTiNi	1.36 x 10-14
2.42	1.99	1100	DAlAlNi	1.90 x 10-14
2.42	1.99	1100	DAlTiNi	4.12 x 10-15
2.42	1.99	1100	DTiAlNi	7.59 x 10-15
2.42	1.99	1100	DTiTiNi	1.82 x 10-14
3.03	1.34	1100	DAlAlNi	2.01 x 10-14
3.03	1.34	1100	DAlTiNi	4.32 x 10-15
3.03	1.34	1100	DTiAlNi	4.50 x 10-15
3.03	1.34	1100	DTiTiNi	1.56 x 10-14

continued

Table 173 (continued)

Ternary Interdiffusion Coefficients for the γ-Phase of the Ni-Al-Ti System

Al (wt%)	Ti (wt%)	Temperature (C)	Coefficient	Value (m2/s)
3.63	0.71	1100	DAlAlNi	2.26 x 10-14
3.63	0.71	1100	DAlTiNi	5.81 x 10-15
3.58	0.67	1000	DAlAlNi	2.99 x 10-15
3.58	0.67	1000	DAlTiNi	6.42 x 10-17
3.58	0.67	1000	DTiAlNi	4.75 x 10-16
3.58	0.67	1000	DTiTiNi	2.05 x 10-15
3.63	0.71	1100	DTiAlNi	4.04 x 10-15
3.63	0.71	1100	DTiTiNi	1.59 x 10-14
1.32	1.81	1200	DAlAlNi	6.90 x 10-14
1.32	1.81	1200	DAlTiNi	1.08 x 10-14
1.32	1.81	1200	DTiAlNi	3.53 x 10-14
1.32	1.81	1200	DTiTiNi	7.50 x 10-14
1.54	1.44	1200	DAlAlNi	6.63 x 10-14
1.54	1.44	1200	DAlTiNi	1.00 x 10-14
1.54	1.44	1200	DTiAlNi	2.22 x 10-14
1.54	1.44	1200	DTiTiNi	6.72 x 10-14
1.81	0.96	1200	DAlAlNi	6.85 x 10-14
1.81	0.96	1200	DAlTiNi	1.28 x 10-14
1.81	0.96	1200	DTiAlNi	1.61 x 10-14
1.81	0.96	1200	DTiTiNi	6.32 x 10-14
1.96	2.51	1200	DAlAlNi	7.02 x 10-14
1.96	2.51	1200	DAlTiNi	2.01 x 10-14
1.96	2.51	1200	DTiAlNi	3.90 x 10-14
1.96	2.51	1200	DTiTiNi	8.16 x 10-14
2.09	0.48	1200	DAlAlNi	6.71 x 10-14
2.09	0.48	1200	DAlTiNi	1.31 x 10-14
2.09	0.48	1200	DTiAlNi	1.09 x 10-14
2.09	0.48	1200	DTiTiNi	5.87 x 10-14

continued

Table 173 (continued)

Ternary Interdiffusion Coefficients for the γ-Phase of the Ni-Al-Ti System

Al (wt%)	Ti (wt%)	Temperature (C)	Coefficient	Value (m2/s)
2.42	2.04	1200	DAlAlNi	7.25 x 10-14
2.42	2.04	1200	DAlTiNi	2.13 x 10-14
2.42	2.04	1200	DTiAlNi	3.08 x 10-14
2.42	2.04	1200	DTiTiNi	7.49 x 10-14
3.01	1.43	1200	DAlAlNi	7.83 x 10-14
3.01	1.43	1200	DAlTiNi	2.80 x 10-14
3.01	1.43	1200	DTiAlNi	2.19 x 10-14
3.01	1.43	1200	DTiTiNi	6.56 x 10-14
3.71	0.74	1200	DAlAlNi	8.39 x 10-14
3.71	0.74	1200	DAlTiNi	4.07 x 10-14
3.71	0.74	1200	DTiAlNi	1.72 x 10-14
3.71	0.74	1200	DTiTiNi	5.64 x 10-14