“He is the Originator of the heavens and the earth…” (Surat al-Anam, 101)
In physics, “shape memory alloy” is an alloy that “remembers” its original, cold-forged shape: returning the pre-deformed shape by heating. This miraculous property occurs while giving heat to metal or in environments where higher temperatures are available. However shape memory is an innate function for spider-spun threads.
The spider thread, the unique structure in nature known to be able to revert its original shape without being exposed to any external effect, is produced by 6 different silk secreted from 6 different sacs. In order to measure the strength of the thread, scientists hanged a spider known as Araneus diadematus and another small object with the same weight with an angle of 90 degree to three threads made up of different materials and twisted them. In this state they recorded how long it took for them to return to their original states. The conclusions were;
Kevlar polymer thread used in bullet-proof vests provides sufficient flexibility yet it could decrease the effect of twisting at a minimum level.
Copper thread had difficulty to return to its original shape and after a few turns it almost came to the point of breaking.
The silk of Araneus diadematus regained its original shape in a very short time.
Let’s think about someone who tries to descend from a high place with the help of a rope. During the descent the rope will constantly twist, turn to right and left and render the action difficult. However such a situation does not hold true for spiders. Fibrils making up the net of the spider prevent the spider to have difficulty while sliding down. This way spider slides down silently in a stable fashion. What offers this opportunity to the spider is the “shape memory” of the thread.
Our Lord created the spider thread which is incomparably stronger and flexible than all other threads with a unique molecular structure that endows it “shape memory”. The molecular structure of proteins making up the silk interpenetrates in a complex fashion. This molecular structure renders the thread resistant against turning. It absorbs the force of distortion and twisting and ensures that it regains its original shape by relaxing after the twist. This way the weight hanging at the end of the rope does not turn right and left because of being subject to the effect of twisting.
The shape memory in nitinol alloy used in industry
The nickel-titanium alloys commercialized under the trade name of Nitinol is the alloy that displays the closest resemblance to the shape memory spider thread possesses in nature.
This metal alloy has features resembling the spider thread but contrary to the spider thread nitinol must be heated up to 90 degree Celsius to make it revert to its initial shape. Nitinol that changes shape according to the given heat can convert into two different shapes or crystal structure.
Accordingly nitinol deforms at temperatures lower than 90 degree Celsius but at higher temperatures it can revert to its original shape. This conversion occurs by linear or planar sliding of atoms over one another.
Even if deformed or distorted, when Nitinol is heated over the temperatures needed for the conversion, atoms which previously changed their places readily slide to their initial locations in the softened structure. This ensures that metal reverts to its original shape.
The place of metals with shape memory in our life
Our All-Mighty Lord offers us many blessings in this world. Metals with shape memory are among these blessings. This property of metals makes it possible to develop many technological products that make our lives easier. Some of them are the following:
Equipment used in open heart surgeries and nervous system operations.
Materials placed in blood vessels that are used to catch clots.
Super elastic glass frames that can resist enormous deformations and revert to their original shapes.
Curved wires used to correct deformations of aesthetical appearance of teeth.
Security valves that are produced to prevent the exit of poisonous and combustible gas in case of a fire.
All Mighty Allah creates with no prior examples
The strong, flexible and non-deforming shape of spider thread and metals that can remember their original shapes although they are inorganic are only a few examples displaying the infinite might of our Lord Who is able to create from nothing. In every detail we see the evidence of All Mighty Allah’s flawless Creation. Every matter, be it organic or inorganic, reminds us His greatness and the blessings He grants us and makes us remember Him and give thanks to Him.
Is He Who creates like him who does not create? So will you not pay heed? If you tried to number Allah’s blessings, you could never count them. Allah is Ever-Forgiving, Most Merciful. (Surat an-Nahl, 17-18)
Take a sheet of paper, crumple it into the shape of a small ball. Then leave it somewhere. In time the paper will slightly open but never revert to its original shape. Yet there is a material in nature that reverts to its former shape. Furthermore while human beings can only produce this material by the help of heat, this material in nature, which is produced by no external intervention, is produced by tiny spiders no longer than a few centimeters.
Nitinol is the material that most resembles spider thread with shape memory. However for a material that is made-of nitinol to revert to its initial state it should absolutely be exposed to high temperatures.
Discovery of shape memory in alloys
The shape memory in alloys was first discovered in 1960s. Nickel-titanium alloys were first developed in Naval Ordnance Laboratories in 1962-1963 and commercialized under the trade name of Nitinol. Their remarkable properties were discovered in an unexpected way. Samples were peened and thus subjected to resistance tests to measure how much force was needed to deform them. Once a few pounds were made on the alloy researchers left the samples in the window pane and left for lunch. When they returned, they saw that the sample stretched back to their original shapes. This great discovery that offers many benefits to humanity occurred by this means Allah created.
The shape memory in spider thread enables the spider to hang upside down no matter what the surrounding conditions may be. This way spider can wait for its hunt silently and without moving. This flawless feature of spider thread is one of the examples of our Lord’s infinite knowledge which is related in the Qur’an with the verse:
“That is because Allah is the Real and gives life to the dead and has power over all things.” (Surat al-Hajj, 6)
How do we benefit from the filters placed in blood vessels?
One of the areas in which alloys with shape memory are used is blood vessels. Filters placed in blood vessels catch clots and save people from life-threatening dangers. For this operation, an anchor-shaped filter made from nickel-titanium wire is flattened before its insertion into blood vessel. Once it is placed into the blood vessel it gets into action with the body heat and stretches back to its initial shape and catches clothes in veins. No doubt that the raw-material of filter is able to benefit from shape memory by the help of heat is only one of the blessings our Lord grants humanity.