尽管铝最近进入了铝，但在未来几十年中，铜仍然将仍然是汽车线束应用中使用的主要材料。那是

Jump to: High-Copper Alloys Numerous Benefits Flex Life

because harness weight can easily be reduced by using finer wires wherever electrically feasible.

Wiring harnesses can account for more than 60 pounds of body weight in cars and light trucks powered by internal-combustion engines. That figure is multiplied several times inelectric and hybrid vehicles, which are expected to become more popular in the next 10 years. In fact, even high-end sportscars are jumping on the bandwagon.

在上个月的日内瓦国际车展上Ferrariunveiled the most advanced and powerful vehicle it has ever developed. The LaFerrari coupe does 0 to 60 mph in less than 3 seconds and produces 963 hp. It is Ferrari’s first gas-electric hybrid, featuring both a V12 engine and a 120-kilowatt electric motor. Engineers at Delphi Automotive developed wiring harnesses for both the low- and high-voltage systems of the vehicle’s electrical-electronic architecture.

To reduce vehicle weight and improve fuel efficiency, automotive engineers around the world are adopting lighter materials, such as aluminum, carbon-fiber composites and magnesium, for many applications. For example, replacing copper wiring with aluminum can reduce the weight of harnesses. However, there are several drawbacks:

• Aluminum conductors are weaker and less fatigue-resistant than copper wires of comparable size, making breakage more likely.
• Aluminum and some of its alloys tend to creep (slowly deform) under low stress. When combined with the metal’s 42 percent higher thermal expansion coefficient compared with copper-based metals and the cyclical nature of automotive temperatures, this tendency causes aluminum-brass and aluminum-copper connections to loosen over time.
• Aluminum loses strength rapidly at even moderately elevated temperatures. And, the metal’s lower volumetric electrical conductivity— only 62 percent that of copper— requires larger-diameter conductors for equivalent ampacity, which makes harnesses more difficult to install.
• Aluminum is more difficult to crimp reliably. Its corrosion resistance, particularly to dissimilar metals, is significantly lower than that of copper-base metals.

High-Copper Alloys

Harness weight can easily be reduced by using finer wires wherever possible. This option exists because fine-gauge conductors are commonly oversized beyond electrical requirements to reduce the risk of breakage when multistrand harnesses must be pulled through tight feed-throughs.

A broken conductor is very costly at that stage of the assembly process. If a break is detected, the damaged harness must be removed and scrapped. If it gets into the field undetected, the electrical malfunctions it causes can create safety problems. At the very least, it reduces the vehicle’s perceived reliability.

Alloying copper cables to raise strength would appear to be a reasonable solution. However, adding alloying elements reduces electrical and thermal conductivities. This is true for all metals, including copper and aluminum. The severity of the reduction varies with the species and amount of elements added, as illustrated in Figure 1.

在最简单的铜合金中，合金元素存在于固体溶液中，或多或少是均匀的单相。大小不同的溶质原子会扭曲相位的晶格，从而增加了强度，但也降低了电导率。

Within limits, the higher the alloy concentration, the greater will be the reduction in conductivity, as illustrated in Figure 2. The effect is additive when more than one alloying element is present. Losses are slightly less severe in fully hardened heat-treatable alloys, since hardening creates precipitates that remove atoms from solution. But, in general, higher strength usually comes with a reduction in conductivity.

The alloy designer’s challenge is, therefore, to achieve a practical balance between strength and conductivity at an acceptable cost. The end user’s challenge is to select the alloy that offers the most suitable strength-conductivity compromise, taking into account such additional factors as product form (rod, wire or strip), ductility for adequate formability, corrosion risk, service temperature and cost.

由于电气和电子工业以及汽车，航空航天和军事制造商的越来越严格的要求，铜制造商的发展是一种持续的追求。由此产生的研究产生了许多新合金，包括高能合金。这些独特的材料比任何现实的替代金属（包括铝）提供了高拉伸强度和更高的电导率。它们还表现出铜的固有腐蚀性。

Numerous Benefits

锻造形式的高能合金含有96％至99.3％的铜，其中包括银色的残余杂质（铸造的高铜合金含量至少为94％的铜和银）。他们分配了从C16000到C19999的统一编号系统名称，分为四个部分：

• Alloys in Part 1 include cadmium copper, beryllium coppers and several multi-constituent coppers, many of which can be heat-treated for maximum strength.
• 第2部分合金包括铬铜合金,chromium-zirconium and zirconium-titanium coppers, plus free-machining copper and a variety of complex alloys. Many of these alloys are also heat-treatable.
• Part 3 alloys contain iron, nickel, tin and silicon in various combinations. Some contain silver for elevated-temperature strength and lead to improved machinability.
• Part 4 alloys rely primarily on combinations of iron, tin, zinc and phosphorus for improved mechanical properties. Some are leaded, as well.

Included among the high-copper alloy family are a small group of materials that deserve mention as potential candidates for automotive wires even though they are not often used in wire form. Technically, they are not even copper alloys; rather, they belong to a separate category of structural materials known as metal-matrix composites (MMCs) and, incorrectly, as dispersion-strengthened “alloys.”

They consist of a nearly-pure copper matrix containing a small amount of extremely fine aluminum oxide (alumina, Al₂o₃) particles that function just like the metallic precipitates that strengthen heat-treated alloys. The difference is that there are no conductivity-lowering alloying elements present. Thus, strength, conductivity and elevated temperature resistance remain high. Corrosion resistance is close to that of pure copper.

这些材料已被用作高性能（RWMA III类）电阻焊接电极以及需要高电导率和长期升高温度抗性的电气和电子产品。尽管高铝含量等级会带来一些困难，但它们可以被吸引到细线中。因此，仅C15720（铝为0.2％₂o_3）is included here.

High-copper alloys are primarily used in high-performance electrical and electronic connectors and components, either as wire (pin-type connectors, windings and conductors for elevated-temperature service) or strip (flat terminals or lead frames). The alloys are listed under SAE specifications J461 and J463 and ASTM specifications B1, B2, B3 and B47.

Flex Life

在连接组件的运动施加的负载下，疲劳不足或支撑不足的电线可能会弯曲和失败。Vibration and strength-lowering elevated temperatures can also increase the likelihood of failure.

各个方案很难量化，几乎不可能在加速测试中模拟资格测试。尽管如此，ASTM B470-02，用于用于电子设备的连接电线的粘合铜导体的标准规范（也称为“ Flex Life”测试）已成为一种广泛使用的和国际认可的方法，用于衡量电气和电气的疲劳耐药性和电子导体。

Results are necessarily qualitative, although the test does provide a repeatable comparison of various conductor materials under user-defined tensile load conditions. The test consists of repeatedly spooling and unspooling a weighted wire around a mandrel. The mandrel diameter, angle of wrap, wire diameter, test temperature and tensile load are fixed by the operator.

2011年的一项研究对德国铜Insti进行tute (DKI) with support from the International Copper Association used a modified version of the ASTM B470-02 test method to evaluate the flex life of 20 copper alloys, including a number of high-copper alloys, plus an aluminum-base wire alloy, copper-clad aluminum and copper-clad steel. Wires were tested at room temperature and at 105 C, in addition to several bend angles and bend radii. Alloys tested by DKI included CuETP/C11000; CuAg0.1/C11600; CuSn0.15/C14415; CuCr1Zr/C18150; CuMg0.14/C15500; and CuCrAgFeTiSi/C18080.

图3比较了5毫米的弯曲半径和60和90度的弯曲角度的弯曲半径上的合金寿命。人们会期望在60度的弯曲半径下的循环失败至少比90度半径的高度高或更高。除了Alloy Cuzr37 R1044（黄色黄铜）外，所有合金都是如此。图中的黑色对角线表示1.0的斜率。

Among the high-copper alloys, highest bend lifetimes were attained in alloys C18150 (CuCr1Zr) and CuMg0.14, which approximates C15500, but contains phosphorus and silver in addition to magnesium. Alloy C18080 (CuCrAgFeTiSi) also performed well. These alloys appear to display the combinations of bend life, tensile strength and conductivity needed in small-gauge automotive electrical wires. However, the widely varying requirements posed by individual applications limit the value of straightforward rankings, and alloys should be selected on a case-by-case basis.

For all test conditions included in the DKI study, the aluminum and copper-clad aluminum wires exhibited the lowest flex lifetimes (red data point at the lower left in Figure 3). But, they should be used with caution, if at all, in situations where fatigue may be an issue. Copper-plated steel wires exhibited the highest flex lifetimes, but their electrical conductivity is considerably lower than any of the copper-base alloys and their weight (density) is considerably higher than that of aluminum.

Based on the highly favorable combination of tensile strength and electrical conductivity offered by the high-copper alloys, in addition to their resistance to bending fatigue, it appears that high-copper alloy would provide viable alternatives to copper itself in highly stressed or fatigue-prone automotive wiring harnesses.