Ultralight alloy might be a game-changer in medical, auto industries

While racing his toy car as a child in Pune, little did Saurabh Nene, today a research scholar with the IITB-Monash Research Academy, imagine that he would one day be involved in path-breaking research to help reduce fuel consumption in the automobile industry. Or help create an alloy that would change the way the medical industry looks at implants in the human body.

The IITB-Monash Research Academy is a collaboration between India and Australia that endeavours to strengthen scientific relationships between the two countries, and graduate research scholars like Saurabh study for a dually-badged PhD from both IIT Bombay and Monash University, spending time at both institutions to enrich their research experience.

Saurabh's project is titled, 'Development of ultralight and ultrafine grained Mg-Li-Ca alloy by compositional optimization and severe plastic deformation' and he is working under the supervision of Prof Bhagwati Prasad Kashyap, Prof Nithyanand Prabhu and Prof Yuri Estrin.

Fig. 1: Applications of light weight Mg alloys in automotives (Courtesy: http://www.totalmateria.com/images/Articles/ktn/Fig246_1.jpg)

In an age of increasing consumption of fuels like petrol and diesel, automobile manufacturers are constantly in the quest for lighter, yet stronger and formable, material which could replace the existing heavy steels in most automotive parts. The reason is simple: a lighter vehicle translates into better mileage.

Among the three classes of materials—metals, polymers and ceramics—polymers have extremely high formability, ceramics are hard and strong, whereas metals succeed in marrying formability with strength.

In the past, manufacturers have attempted to reduce the weight of vehicles by experimenting with different polymer matrix composites while creating automobile parts. However, since these experiments have not yielded much, they are now trying to develop ultralight alloys. And this is where Saurabh's work could make a significant contribution

After extensive literature studies on alloys, Saurabh chose Magnesium (Mg) as his base material. "Magnesium, though lightweight, has high specific strength and is comparatively inexpensive. Besides, it is bio-compatible, which means it can interact with the human body as well, which opens up a number other possible medical applications—for instance as implants," he explains.

Fig. 2: Mg alloy implanted in the body (Courtesy: Heidrun Hillen, Press Release: Helmholtz-ZentrumGeesthacht, Max-Planck-Straße 121502 Geesthacht)

"Commercially used titanium-based implants in the human body are found to be very heavy and need to be removed by surgery once the healing of the bone is over. Thus, if a material can be designed which upon implantation inside the body could dissolve as the healing progresses, it could have a significant application in the field of medicine. We have therefore designed and developed a new ultralight alloy which could be useful as a degradable implant material in the human body as well as for automobile and aerospace applications.

He further added, "We chose two alloying elements—Lithium (Li) and Calcium (Ca)—which when added in Magnesium, create a new ternary alloy, designated as Mg-4Li-1Ca (LC41) alloy. Lithium, being the lightest among metals (0.5 g/cc), will reduce the density of the alloy and also help improve the room temperature formability. Calcium, on the other hand, being an inherent part of the human bone, will enhance biocompatibility and help in effective bio-degradation. We have achieved a density as low as 1.47 g/cc for Mg-4Li-1Ca (LC41), which is comparable with even commercial polymers."

Fig. 3: Specific strength vs. elongation to failure for a range of Mg alloys. Red diamond: LX41; blue square: Mg-30Li; further symbols correspond to literature data for other hotrolled Mg alloys and are explained in the original publication [Y. Estrin et al., Materials Letters 173, 252–256 (2016)]

"The IITB-Monash Research Academy is an opportunity for industry in Australia and India, as well as for IIT Bombay and Monash University, to train the next generation of rich talent in India. The 'Academy', therefore, has the potential to be a significant research institution. Talent from the Academy should become much sought after around the globe," says Dr Murali Sastry, CEO, IITB-Monash Research Academy.

"Because the alloy is degradable and will dissolve in the human body, it will reduce the requirement for a second surgery. Besides, implant-based operations will become less complicated, cheaper, and less painful, since the alloy will itself degrade in the body as the bone heals. What's more, the automobile and aerospace industries will get a good substitute for making heavy components, which should drastically reduce fuel consumption," he says with his trademark boyish grin.

And, why not? The boy with the toy car is clearly going places.

Research scholar: Saurabh Nene, IITB-Monash Research Academy

Project title: Development of ultralight and ultrafine grained Mg-Li-Ca alloy by compositional optimization and severe plastic deformation

Supervisors: Prof Bhagwati Prasad Kashyap, Prof Nithyanand Prabhu, Prof Yuri Estrin

Contact details: nenesaurabh@gmail.com

This story was written by Mr Krishna Warrier based on inputs from the research student and IITB-Monash Research Academy. Copyright IITB-Monash Research Academy.