Diamond turning and polishing tests on new RSP aluminum alloys

AE Monitoring of Diamond Turned Rapidly Soldified Aluminium 443

“…Conventional aluminium materials are produced through powder metallurgy which cannot achieve the best uniformity of the alloying elements [2,6]. Rapid solidification can be used to achieve the following: formation of new metastable phases, extension of the solid solubility to give precipitate strengthening and solute strengthening and refinement of the grain size of the matrix and other constituents to give fine grain strengthening [7][8][9].…”

“…This process helps to manufacture uniform aluminium alloys with small grain sizes hence reducing the use of exorbitant and vulnerable plating to achieve lower surface roughness values [1]. Furthermore, rapidly solidified aluminium alloys contain fewer impurities which is advantageous as it reduces the chances of break outs occurring during subsequent polishing [2]. The fundamental principle in rapid solidification process is the removal of heat from a mass of liquid metal at a fast rate.…”

“…The ribbon is chopped to flakes and gathered in a vessel at high cooling rates in the range of 1Mk/s. The flakes are degassed and subjected to hot isostatic pressure at which a consolidated material can be realized in the form of billets [2]. These billets can be further extruded or forged to required dimensions.…”

“…Reasons are understandably from its reflective properties, high specific stiffness and the ability maintain the coefficient of thermal expansion when subjected to severe temperature conditions [1,2]. Furthermore, a low cost is incurred while applying AA6061 to astronomy due to sufficient available data on this material, hence selecting the material does not require new certification trajectories [1].…”

Investigation of diamond turning: of rapidly solidified aluminum alloys

“…Currently, materials typically used for manufacturing metal mirrors in optical applications are aluminum and copper, because these are easily processed using single-point diamond turning (SPDT) technology. However, conventional aluminum can be diamond turned to achieve surface roughness (Ra) values of approximately 4 to 8 nm, which is adequate for applications that involve the infrared spectral range, but not for the near-ultraviolet wavelength (NUV) spectral range because the alloying elements in conventional aluminum material made using powder metallurgy processes are not uniform [1][2][3]. A recently developed rapid solidification process was realized using a melt spinning operation, which refines the grain size of alloys by 10 to 50 times compared with that in conventional aluminum 6061; the resulting alloy is called RSA 6061.…”