Appeal No. 2004-0109
Application 09/324,549
Appellants allege that they “have demonstrated that the use of small amounts of Li in Al-
Zn-Cu-Mg alloys, as presently claimed, results in an unexpected increase in the mechanical
properties of the alloys” as seen from “Fig. 1 of the application [which] demonstrates that the use
of the claimed range of from about 0.10 to 4.0 wt % lithium improves the yield strengths of the
alloys in comparison with similar alloys containing either no lithium, or a greater amount of
lithium” (brief, page 14). Appellants point out that
the leftmost set of data points in Fig. 1 are for “Aging Condition No. 1” which
corresponds to a T3 aging condition. Alloy D (0.62 wt % Li) which is outside the
presently claimed alloy range has a significantly lower Tensile Yield Strength in the
T3 condition than either Alloy B (0.25 wt % Li) or Alloy C (0.36 wt % Li) which are
inside the presently claimed alloy range. As a further example, the set of data points
for Aging Condition No. 6 in Fig. 1 demonstrates that Alloys B and C within the
presently claimed alloy range have significantly higher Tensile Yield Strengths than
Alloy A (zero Li) which is outside the presently claimed alloy range.” [Id., page 15.]
Appellants submit in the brief FIG. 1a which
presents the data in Fig. 1 in a different way. Fig. 1a plots Tensile Yield Strength
(TYS) versus Li amount for the data sets in Fig, 1 corresponding to Aging conditions
No. 1 (T3 condition) and Aging Condition No. 6 (T8 condition).
. . . .
As shown in Fig. 1a, in the T3 condition, the Tensile Yield Strength of Alloy D
having 0.62 wt % Li drops off significantly in comparison with the Tensile Yield
Strength of Alloys B and C having 0.25 wt % Li and 0.36 wt % Li, respectively. Fig.
1a also shows that, in the T8 condition corresponding to Aging Condition No. 6 in Fig.
1, the Tensile Yield Strengths of Alloys B and C are significantly higher in comparison
with Alloy A having no lithium.
The foregoing figures demonstrate that unexpectedly improved yield strengths are
achieved by adding the small amount of Li recited in Claim 19. The improved yield
strengths achieved with the presently claimed alloy are particularly surprising in view
of the teachings of the cited references, which direct those skilled in the art not to use
less than 0.5 wt % Li. [Id., pages 15-16.]
The examiner found in the Office action of June 18, 2002, that in Fig. 1, alloy D “has
better tensile yield strength than alloy B . . . in conditions 2 and 8;” that “conditions 4-7, alloy B
and alloy D have substantially same/overlap tensile yield strengths;” and that “tensile yield
strengths of claimed alloy C . . . has less than 7% difference from alloy D in all conditions,” and
conclusion that “instant figure 1 fails to show the claimed Li range is critical from end-point to
end-point.” (Paper No. 14, page 5; see also answer, page 6). In response, appellants argue “that
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