Appeal 2007-2359
Application 90/006,951
63. EP instructs that if the Si content is too low, the alloy strength
becomes too low, while if the Si content is too high, the extrudability
becomes too low. (EP at 3:12-14.)
64. According to EP, the Fe is present in an as-cast alloy ingot as large
plate-like β-AlFeSi particles, which are preferably homogenized to convert
the β-form to the α-form. (EP at 3:15–18.)
65. EP states that it was known that excess Si (as defined supra) stabilizes
the β-AlFeSi form, "which has a detrimental effect on extrudability and in
particular on extrusion surface quality." (EP at 3:18–20.)
66. EP states that "Mn is included in the alloys in order to improve
extrusion surface quality. Mn acts to accelerate the β to α-AlFeSi
transformation during homogenisation, so that the resulting homogenised
ingot has improved extrudability, that is to say improved extrusion surface
quality." (EP at 3:22–24.)
67. EP teaches that following homogenization at 550–600°C, the hot
homogenized ingot is extruded under conventional hot extrusion conditions
and quenched, preferably in still air. (EP at 3:34–40.)
68. According to EP, aging at 150–200°C for 1–48 hours, yielding
ultimate tensile strengths "of at least 240 MPa, often greater than 250 MPa,
with acceptable toughness." (EP at 3:42–50.)
69. Comparison of the EP alloy composition ranges with the 359 patent
composition ranges on appeal shows that there is substantial overlap for all
components except for Si:
EP 359 Patent
Mg 0.25–0.40 0.20–0.34
13
Page: Previous 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 Next
Last modified: September 9, 2013