Through Severe Plastic Deformation (SPD) processing, Metallicum can reduce the grain size of conventional metals from the typical range of 10 to 50 μm to a range between 20 and 500 nm.
Metallicum Inc., an offshoot of Los Alamos National Laboratory that was recently acquired by Manhattan Scientifics, has figured out a way to manufacture nanostructured metals and alloys—“to change the internal structure of virtually any polycrystalline metal so it is much stronger than its conventional counterpart,” said Terry Lowe, co-inventor of the nanostructuring process and President of the Metallicum division.
The process, called Severe Plastic Deformation (SPD), creates metals 30 to 100% stronger than conventional grades. “A lightweight industrial metal, like aluminum, can be manufactured to have the strength of steel,” said Lowe. “So all of the sudden you can use aluminum for things that you would never even conceive of it being used for.”
The improvement in strength, as well as other enhanced properties, can be attributed to reducing the size of a material’s grains (or crystals)—comparable to the diameter of a human hair to begin with—by a factor of 500 to 1000. “We devised methods that deform metals, but without changing their geometry,” Lowe explained. “We subject materials to intense, localized shearing, which basically causes the grains to want to rotate or spin. As they rotate, what really happens is they break up into smaller grains, and you form new boundaries.”
The characteristics of the grain boundaries then can be altered to increase metal ductility, the ability to resist failure, and to customize the properties of the metal at its surfaces. “The limiting property in many [transportation] applications…is not strength; it’s fatigue—the ability to resist cyclic loadings,” Lowe said, adding that the SPD process results in “dramatically” increased fatigue resistance—by an amount comparable to the increase in strength.
The main “green” benefit of the technology lies in the fact that if you enhance the strength and other characteristics of a material, then you can use less of it in the final component design. “Basically, you’re just moving around a lot less metal,” Lowe said, positively impacting the amount of fuel used. “A big airplane like a B747 has about 100,000 lb of titanium in its construction. We believe our nano metals could reduce that weight by about 5% or 5000 lb.”
Lowe referred to nanostructured metals as “drop-in technology” because they can simply replace their conventional form in current applications while meeting or exceeding all specs. “It isn’t some novel, fancy material; it’s the same material,” he said.
Another green aspect is that the process is performed at low temperatures. “For alloys that you would typically process at elevated temperatures—titanium, for example, typically above 800°C—we can process at room temperature or up to 500°C,” said Lowe, noting that tool life and surface finish improve because of the material’s ease of machineability. And nanostructured metals are ideal for complex shapes, he added, because they are super plastic at low temperatures.
“Typically, super plasticity is expensive. You’ll spend 20 minutes to four hours pressing a single part, but with our material you do the same thing in a matter of seconds because they’re super plastic at 10 to 100 times greater rates,” said Lowe. “So you can do near-net-shape forming, but really quickly. And you can do that with materials that aren’t traditionally even super plastic.”
Beyond aluminum and titanium, Metallicum has used its SPD process on a variety of materials including steel, beryllium, magnesium, nickel, cobalt-chromium, and even polymers and silicon. “It’s a deliberate choice to focus on titanium [first],” said Lowe, with initial application in the biomedical field. “The first day on the market, you want to address the smaller-volume applications, which have a very high margin. Generally in the transportation industry, your manufacturing practice has to be very mature to be cost effective, and that’s probably more than a year off.”
“It’s really just a matter of scale,” Lowe continued. “And there’s nothing that prevents us from adjusting that scale; the question is, when is it most appropriate to do that?”
Metallicum has identified more than 100 different applications for the technology and is currently in the second generation of the continuous processing methodology. The process is capable of producing rod and bar up to 40 mm in diameter to be formed into anything from car parts to heart stents.
Cost should not be a deal-breaker, believes Lowe, because “our methods are intrinsically mechanical processing methods; they’re not fundamentally different from rolling, extrusion, and other similar technologies.” Savings that result from using less material help, too.
Currently, the company is in different stages of development and evaluation with at least two major automakers, one heavy-equipment manufacturer, and two major aerospace companies.
參考譯文：
通過深度的塑性變形（SPD）處理后，金屬晶粒大小可從典型的10到50μm減小至20至500nm之間 。
該金屬公司是羅斯.阿拉母斯國家實驗室的一個分支，曼哈頓科學(xué)院最近才將其合并；納米結(jié)構(gòu)處理技術(shù)的共同發(fā)現(xiàn)人兼金屬研究支部的主管Terry Lowe說，這個公司發(fā)現(xiàn)了制造納米金屬及其合金的辦法，即可通過改變?nèi)魏味嗑w的實際內(nèi)部結(jié)構(gòu)從而使之比原有結(jié)構(gòu)更加強。
這種稱之為做深度塑性變形的處理技術(shù)，可以使得金屬的強度比原有級別提高30%到100%?！跋皲X合金一樣的工業(yè)輕量化金屬可以擁有和鋼一樣的強度“，Lowe說，“因此，在很多情況下，你可以突破常規(guī)采用鋁合金材料，而在此之前，卻從未想過應(yīng)用這種金屬”。
材料強度上的提高以及其他特性的增強是由于其晶粒（晶體）尺寸（與人的頭發(fā)直徑相仿）減小了500到1000倍；“我們只是找到了一種方法使金屬成型，但并不改變其幾何結(jié)構(gòu)”，Lowe解釋說，“我們讓材料受到強烈的局部剪切作用，這種作用可引起晶粒的旋轉(zhuǎn)，當(dāng)晶粒旋轉(zhuǎn)時，所發(fā)生的是晶粒變成了更小的晶粒，而你卻得到新的晶界線”。
晶粒界限特性可被改變以增加金屬的塑性，即金屬抗疲勞的能力，并根據(jù)需要在金屬表面形成相應(yīng)的特性?！岸鄶?shù)應(yīng)用環(huán)境（交通）對材料的要求并不是強度，而是其疲勞特性-抵御周期載荷的能力“,Lowe說。而SPD處理可顯著地增加其疲老特性，且疲勞強度的增加幅度大于強度上的增加幅度。
該技術(shù)是一項綠色的技術(shù)，它體現(xiàn)在使材料強度以及其他特性增加的同時，結(jié)構(gòu)設(shè)計可以使用更少的材料?！盎旧?，在減少材料的使用量時，你一直在猶豫“，Lowe說，這將肯定將對能源的使用產(chǎn)生沖擊，“向B747一樣的大型支線客機結(jié)構(gòu)大約使用了大約100000lb的Ti，我們相信我們的納米金屬可以使該結(jié)構(gòu)的重量減少5%或5000lb”。
Lowe 將納米金屬稱為革命性的技術(shù)，因為它可以輕易取代當(dāng)前應(yīng)用的傳統(tǒng)成型方式，并且滿足或超過所有的材料種類。“它不是小說中想象出來的材料，它還是同一種材料”，他說。
另一個綠色應(yīng)用是該處理方法是在低溫下進行的，“通常，合金的處理在高溫下進行-如Ti，通常高于800°C-而我們可以在室溫至500°C的溫度下進行處理”，Lowe說，工具的壽命及表面質(zhì)量的得到了改進，這是由于材料的機加工性能提高了，納米結(jié)構(gòu)金屬是復(fù)雜結(jié)構(gòu)的理想選用材料，他附加說到，這是由于它在低溫下是超彈性的。
“一般地，超彈性是較昂貴的，你不得不用20分鐘到4個小時的時間處理一個零部件，但如果采用我們的材料，做同樣的事只需要幾十秒，因為它擁有10到100倍的超彈性”Lowe說，“因此，你可以迅速做成類似網(wǎng)狀的形狀，并且這樣做不是采用 傳統(tǒng)意義上的超彈性“。
除了鋁和Ti外，可使用SPD處理的金屬有鋼，Be，Mg，Ni，Co-Cr，甚至聚合物和Si；“將關(guān)注集中在Ti上是明智的“,Lowe說，最初僅是應(yīng)用在生物醫(yī)藥領(lǐng)域，“投入市場之日，你所想到的是那些使用量小但獲利頗豐的項目。通常在交通工業(yè)，你的制造經(jīng)驗需要非常成熟使得成本經(jīng)濟，這可能需要1年以上的時間。
該金屬研究機構(gòu)已發(fā)現(xiàn)這種技術(shù)可以有多于100種不同的應(yīng)用，并且，目前這種連續(xù)處理方法正處于第二階段，該處理技術(shù)可生產(chǎn)直徑達(dá)到40mm的棒材及線材，并應(yīng)用到從汽車部件到機槍扳機的任何場合中。
成本不會成為交易的阻礙，相信Lowe，因為，“我們的方法本質(zhì)上就是機械處理方法，它在基本原理上和軋制，擠壓，以及其他類似技術(shù)并無不同“，并且，因為采使用較少的材料可獲得相應(yīng)的結(jié)余。
目前，對這項應(yīng)用進行開發(fā)及評估等不同階段的公司至少有兩個汽車公司，一個重型設(shè)備制造公司，以及兩個主要的航空公司。
（轉(zhuǎn)載）
