Characteristics of aluminium–scandium alloy thin sheets obtained by physical vapour deposition

• Published in: Materials in engineering 2010-06, Vol.31, p.S76-S81
• Main Authors: Stock, H.-R., Köhler, B., Bomas, H., Zoch, H.-W.
• Format: Article
• Language: English
• Subjects: A. Non-ferros metals and alloys; Aging; Aluminium–scandium alloy; Artificial ageing; B. Film and sheet; C. Vapour deposition; Columnar structure; Cracks; Deposition; Dissolution; Magnetron sputtering; Physical vapour deposition; Sheet metal; Tensile properties; Tensile strength; Tensile tests; Thin sheets
• ISSN: 0261-3069
• DOI: 10.1016/j.matdes.2010.04.040

Thin sheets of an age-hardenable aluminium–scandium alloy were deposited by direct current magnetron sputtering. As targets an aluminium–scandium pre-alloy with a scandium content of 2.0 mass% (size 88 × 500 mm) was applied. The substrates to be coated consisted of thin steel sheets which after deposition were dissolved in an oxidizing medium. In this way, free-standing sheets of less than 30 μm thickness of the aluminium–scandium alloy were received. Two deposition temperatures, 37 and 160 °C, were applied. The as-received sheets showed a typical columnar structure. Two post-treatments of the sheets were applied: a cold isostatic pressing and an artificial ageing for 1 h at temperatures between 200 and 400 °C. The strength of the sheets was measured by tensile tests. The employed specimens had a width of 10 mm and were gained from the sheets by cutting. During testing, load and strain were measured by a 1000 N load cell and a video extensometer, respectively. The as-deposited specimens show a tensile strength of 350 MPa. Artificial ageing at 300 °C increases the tensile strength to more than 400 MPa. It could be shown that during tensile tests cracks are initialized at coating defects.