In the central part of Austria lies Leoben City, where research experts with a new heat treatment develop an aluminium alloy strong and easily malleable concurrently. This unique light material can therefore be utilized regularly in the automotive industry.
The three vital requirements that auto manufacturers place on the body shell are lightweight, very strong and easily malleable at the same time.
The metal aluminium is around three times lighter than conventional steel, but the increase in strength is unfortunately usually associated with a decrease in formability. Researchers in Leoben have found a way to make aluminium alloys more easily deformable while maintaining high strength.
The battle is for every gram, as for car manufacturers, the specifications for reducing CO2 emissions and saving energy consumption mean that lightweight construction is given high priority because it saves energy when driving. In addition to carbon, light aluminium is considered a flare of hope in the area of weight reduction.
However, the composite lightweight components make it necessary for the material to be highly malleable, while at the same time they should be damaged as little as possible in the event of an accident or hail and should prove their strength.
Dr Stefan Pogatscher, Chairman of non-ferrous metallurgy at the Montanuni Leoben said: “However, because the ratio of strength to formability is still unfavourable in aluminium alloys, aluminium materials cannot simply replace the heavier steel in mass use currently in mass use.”
To achieve better material properties, he deals with the atomic processes in the early phase of the hardening of aluminium alloys and also heads the Christian Doppler (CD) laboratory for advanced aluminium alloys in Leoben. The new way of heat treatment found by him and his team led to the desired goal.
“Scientists have moved away from the usual heat treatment, which consists of a one-time rapid quenching of the warm aluminium alloy. You turn the tables and rely on repeated rapid heating and medium temperature. Accordingly, the method is not called ‘quenching but rather ‘up-quenching. By repeated brief heating to a medium temperature, properties can be created within a few hours that can otherwise only be achieved in an uneconomically long period of more than a week," says Florian Schmid from the Leoben CD Laboratory.
Dr Pogatscher explained the underlying, atomic cause of the method's success: "The new process accelerates the formation of nanometer-sized atom clusters, which enable high strength and good deformability at the same time. The cluster formation is driven by a mechanism of missing atoms. It works like one with figures occupied chessboard, where the pieces represent the atoms in the material. If all fields are occupied, the pieces - i.e. the atoms - cannot move. Only when pieces are missing are they movable. With the pendulum between brief heating and cooling, we succeeded more to 'pump' voids into the material and thereby accelerate the atom transport and thus the cluster formation.”
“A similarly hard and malleable aluminium alloy can also be produced using conventional heat treatment that takes months, but the waiting time is now reduced by 95%, as Dr Pogatscher added.
The new solution was developed in cooperation with the Austrian aluminium manufacturer AMAG.
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