Magnesium, or Mg, once prized only for what it could do for race cars and aerospace, is gradually gaining the appreciation that it deserves. Do you like oxygen? I hope you do. Without magnesium, there would be no photosynthesis. Do you like living? Good, because it is essential to all cellular life that we know of. It is the third most commonly used structural metal, 8th most abundant element in the Earth’s crust, 4th most common element in the Earth (in total), 9th most abundant in the known universe, burns at 3,100 °C, ignites at 473 °C and was commonly used by railroad crews to start the thermite reaction that melted rail ends together. In short, it is as important to our life, and modern life, as any element we know.
Still, magnesium does not get the respect it is due outside of auto enthusiasts, aerospace, and biologists. It is not a rare element, so it does not command a high price. It is highly reactive with oxygen, requiring that it be painted/passivated, therefor it does not have the beautiful appearance of some metals. One clue to its undeserved obscurity is its flammability. Some cities and municipalities ban the machining of magnesium. Once a common material for wheels, it was replaced by aluminum alloys after mag wheels started bursting into pyrotechnical flames. Further, while it is extremely stiff, it can be shattered due to the same rigidity. That is why magnesium is usually an alloy, with added elements to increase malleability and raise the self-ignition temperature. In its alloy forms, magnesium is being used in engine blocks, where the alloying elements increase the self-ignition point to levels sufficiently high for them to be used in passenger cars. So, the relative obscurity compared to aluminum has NOTHING to do with any superiority of aluminum over magnesium. Rather, it is due to “conventional wisdom” that magnesium is dangerous to machine. As the desire for greater fuel economy advances the use of magnesium and magnesium alloys in passenger vehicles, this apprehension will disappear, and magnesium will become more common. Tiglon is one of a very few companies that bucks the conventional wisdom in the search for ultimate performance.
Regardless, some hazardous materials are being used in audio equipment to this day, including beryllium and thorium. Considering the advantages, it’s no wonder that manufacturers started selling magnesium headshells and tonearms. Magnesium benefits used by Tiglon include light weight, stiffness, strength, vibration damping and shielding against EMI/RFI. So, all things being equal, structures that use magnesium will be lighter, yet more rigid, while being quieter than an equivalent product made of aluminum. TiGLON chose magnesium for these reasons, and not because magnesium is easy to work with, but in spite of the fact that it is not easy to work with.
According to the Reynolds Company, “Magnesium alloys have good vibration damping characteristics due to the low stiffness modulus”.
According to a research paper from Linköping University in Sweden, in collaboration with Drexel University, Philadelphia, PA, hexagonal metals (Mg is classified as a “hexagonal close-packed” metal) are self-damped due to a unique internal “reversible closed hysteresis stress-strain loops”. According to the article:
“Hexagonal metals, HM, have been studied for decades due to their technological importance. While their mechanisms for plastic deformation to high strains are widely accepted, their low-strain (ε < 1%) behavior has, until recently, not been very well understood. The deformation of HM to low strains is a crucial piece of the deformation puzzle for HM, especially when considering phenomena such as microyielding and damping. A breakthrough toward understanding the early deformation of HM came about recently when we showed that they are kinking nonlinear elastic, KNE, solids. Macroscopically, KNE solids are characterized by the formation of fully, and spontaneously, reversible closed hysteresis stress-strain loops. The size of these loops, which corresponds to the energy dissipated per unit volume, scales with the maximum applied stress squared and is a strong function of grain size. It is currently postulated that the deformation mechanism that leads to these characteristic stress-strain loops is the nucleation, growth, and annihilation of the incipient kink bands, IKBs.
IKBs (Fig. 1a) are concentric dislocation loops that nucleate and grow under an applied load, and spontaneously annihilate when the load is remove. A sufficient condition for a solid to be KNE is plastic anisotropy where the dislocations are confined to two dimensions–usually the basal planes in hexagonal metals. Characteristics that often lead to this include a high c/a ratio and low c44, where c and a are the lattice constants of the unit cell and c44 is the second-order elastic shear constant. Most layered solids, graphite, the Mn+1AXn phases, and mica can also classified as KNE solids, among others.”Click here to view the full article, with citations.
Magnesium benefits used by TiGLON
The first, and most important characteristic for audio use is the damped nature of magnesium. The magnesium usage by Tiglon centers around its ability to stop or damp vibration. To show the relative merit of Mg, Tiglon prepared this chart showing the relative resonance levels in proper materials used in audio.
A secondary benefit for audio, one that has benefits just as important as damping, is the shielding ability of magnesium. For RFI, magnesium is as effective as most competing metals, and due to its low mass, is used as a shield of choice in many high performance aerospace applications. It is also effective against EMI, but not as much as traditional materials like copper. Tiglon’s cables combine alternating layers of copper braid and magnesium ribbon to take advantage of the excellent damping and RFI shielding of magnesium, plus the excellent EMI shielding of copper. It is the best of both worlds. To show the shielding benefits of magnesium, Tiglon prepared this graph showing the relative merits of different shielding materials.
It should be readily apparent that magnesium is the material of choice for audio use. Tiglon leads the way with award winning products of excellent sonic merit.
The patent application from Okino-san, president of TiGLON and Shindoh-san:
Highly Advanced Conductors
Besides Tiglon’s development of magnesium applications in audio, it will always be seeking to improve other aspects of performance. Recently introduced to the product line, the MGL-X10 uses the newly developed “HiFC” copper conductor from Hitachi Metals, LTD.
From Hitachi Metals LTD literature:
New Generation of Electro-Conductive Material
with Greater Malleability and Longer Bending Fatigue Resiliance
High functional pure copper HiFC is a new generation pure copper with various advantages including almost same softening characteristic as high-purity 6N copper (approximately 99.9999%). HiFC can be produced by continuous casting and hot rolling and its special characteristic was achieved by adding trace amounts of titanium into copper.
We are proceeding research and development of HiFC as an electro-conductive material in wide range market fields, for example, power electric field, medical instrument field, and information & telecommunication field. And we are going to apply HiFC for advance practical products such as electric wires, cables, and wiring materials.
Main characteristics of HiFC
|(1)||Low-temperature softening characteristic such as high-purity copper (see Fig. 1)|
|(2)||Superior elongation performance due to fine crystal grains formed by controlling metallurgical structures (see Fig.2 and Fig.3)|
|(3)||Both softness and long bending fatigue life time made possible by controlling metallurgical structure. (see Fig. 4)|
|(4)||High conductivity (> 101% IACS)|
|(5)||Excellent welding performance equal to oxygen-free copper wire|
|(6)||High performance material produced by continuous casting and rolling|
Fig. 1: Softening characteristic of pure copper HiFC
Fig. 2: Elongation characteristic of pure copper HiFC
Fig. 3: Comparison of crystal gain size of pure coppers annealed at 500°C for 1 hour
Fig. 4: Metallurgical structure of fine crystal grain size observed on surface of pure copper HiFC comparing with homogeneous grain size of OFC annealed at 600°C for 1 hour
By Phillip Holmes