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.
参考译文：
通过深度的塑性变形（SPD）处理后，金属晶粒大小可从典型的10到50µm减小至20至500nm之间 。
该金属公司是罗斯.阿拉母斯国家实验室的一个分支，曼哈顿科学院最近才将其合并；纳米结构处理技术的共同发现人兼金属研究支部的主管Terry Lowe说，这个公司发现了制造纳米金属及其合金的办法，即可通过改变任何多晶体的实际内部结构从而使之比原有结构更加强。
这种称之为做深度塑性变形的处理技术，可以使得金属的强度比原有级别提高30%到100%。“像铝合金一样的工业轻量化金属可以拥有和钢一样的强度“，Lowe说，“因此，在很多情况下，你可以突破常规采用铝合金材料，而在此之前，却从未想过应用这种金属”。
材料强度上的提高以及其他特性的增强是由于其晶粒（晶体）尺寸（与人的头发直径相仿）减小了500到1000倍；“我们只是找到了一种方法使金属成型，但并不改变其几何结构”，Lowe解释说，“我们让材料受到强烈的局部剪切作用，这种作用可引起晶粒的旋转，当晶粒旋转时，所发生的是晶粒变成了更小的晶粒，而你却得到新的晶界线”。
晶粒界限特性可被改变以增加金属的塑性，即金属抗疲劳的能力，并根据需要在金属表面形成相应的特性。“多数应用环境（交通）对材料的要求并不是强度，而是其疲劳特性-抵御周期载荷的能力“,Lowe说。而SPD处理可显著地增加其疲老特性，且疲劳强度的增加幅度大于强度上的增加幅度。
该技术是一项绿色的技术，它体现在使材料强度以及其他特性增加的同时，结构设计可以使用更少的材料。“基本上，在减少材料的使用量时，你一直在犹豫“，Lowe说，这将肯定将对能源的使用产生冲击，“向B747一样的大型支线客机结构大约使用了大约100000lb的Ti，我们相信我们的纳米金属可以使该结构的重量减少5%或5000lb”。
Lowe 将纳米金属称为革命性的技术，因为它可以轻易取代当前应用的传统成型方式，并且满足或超过所有的材料种类。“它不是小说中想象出来的材料，它还是同一种材料”，他说。
另一个绿色应用是该处理方法是在低温下进行的，“通常，合金的处理在高温下进行-如Ti，通常高于800°C-而我们可以在室温至500°C的温度下进行处理”，Lowe说，工具的寿命及表面质量的得到了改进，这是由于材料的机加工性能提高了，纳米结构金属是复杂结构的理想选用材料，他附加说到，这是由于它在低温下是超弹性的。
“一般地，超弹性是较昂贵的，你不得不用20分钟到4个小时的时间处理一个零部件，但如果采用我们的材料，做同样的事只需要几十秒，因为它拥有10到100倍的超弹性”Lowe说，“因此，你可以迅速做成类似网状的形状，并且这样做不是采用 传统意义上的超弹性“。
除了铝和Ti外，可使用SPD处理的金属有钢，Be，Mg，Ni，Co-Cr，甚至聚合物和Si；“将关注集中在Ti上是明智的“,Lowe说，最初仅是应用在生物医药领域，“投入市场之日，你所想到的是那些使用量小但获利颇丰的项目。通常在交通工业，你的制造经验需要非常成熟使得成本经济，这可能需要1年以上的时间。
该金属研究机构已发现这种技术可以有多于100种不同的应用，并且，目前这种连续处理方法正处于第二阶段，该处理技术可生产直径达到40mm的棒材及线材，并应用到从汽车部件到机枪扳机的任何场合中。
成本不会成为交易的阻碍，相信Lowe，因为，“我们的方法本质上就是机械处理方法，它在基本原理上和轧制，挤压，以及其他类似技术并无不同“，并且，因为采使用较少的材料可获得相应的结余。
目前，对这项应用进行开发及评估等不同阶段的公司至少有两个汽车公司，一个重型设备制造公司，以及两个主要的航空公司。
（转载）
