Classification of nickel-based alloys

According to the main properties, it can be divided into nickel-based heat-resistant alloy, nickel-based corrosion-resistant alloy, nickel-based wear-resistant alloy, nickel-based precision alloy and nickel-based shape memory alloy.

corrosion resisting nickelbase alloys

The main alloying elements are copper, chromium and molybdenum. It has good comprehensive properties and can resist all kinds of acid corrosion and stress corrosion. Nickel-copper (Ni-Cu) alloy, also known as Monel alloy, was first used (produced in America in 1905). In addition, there are nickel-chromium (Ni-Cr) alloy (that is, nickel-based heat-resistant alloy, heat-resistant corrosion-resistant alloy in corrosion-resistant alloy) and nickel-molybdenum (Ni-Mo) alloy (mainly referring to Hastelloy B series, and domestic professional corrosion-resistant alloy manufacturers include Beijing Iron and Steel Research Institute.Beijing Rongpin Technology Co., Ltd., Baoti Group Rare Metal Materials Company, etc.). At the same time, pure nickel is also a typical representative of nickel-based corrosion-resistant alloys. These nickel-based corrosion-resistant alloys are mainly used to manufacture various parts for corrosion-resistant environment such as petroleum, chemical industry and electric power. Most nickel-based corrosion-resistant alloys have austenite structure. In the state of solution and aging treatment, there are intermetallic phases and metal carbonitrides on the austenite matrix and grain boundary of the alloy. Various corrosion-resistant alloys are classified according to their components and their characteristics are as follows:

The corrosion resistance of Ni-Cu alloy is better than that of nickel in reducing medium, and better than that of copper in oxidizing medium. It is the best material with high temperature resistance to fluorine gas, hydrogen fluoride and hydrofluoric acid in the absence of oxygen and oxidant (see metal corrosion).

Ni-Cr alloy is also a nickel-based heat-resistant alloy; It is mainly used under the condition of oxidizing medium. It is resistant to high temperature oxidation and corrosion of gases containing sulfur and vanadium, and its corrosion resistance increases with the increase of chromium content. This kind of alloy also has good resistance to hydroxide (such as NaOH and KOH) corrosion and stress corrosion.

Ni-Mo alloy is mainly used under the condition of reducing medium corrosion. It is the best alloy with hydrochloric acid corrosion resistance, but in the presence of oxygen and oxidant, the corrosion resistance will decrease significantly.

Ni-Cr-Mo(W) alloy has the properties of the above Ni-Cr alloy and Ni-Mo alloy. It is mainly used under the condition of oxidation-reduction mixed medium. This kind of alloy has good corrosion resistance in high temperature hydrogen fluoride gas, hydrochloric acid and hydrofluoric acid solution containing oxygen and oxidant, and wet chlorine at room temperature.

Ni-Cr-Mo-Cu alloy has the ability to resist both nitric acid and sulfuric acid corrosion, and also has good corrosion resistance in some oxidation-reduction mixed acids.

Nickel-based wear-resistant alloy

The main alloying elements are chromium, molybdenum and tungsten, but also contain a small amount of niobium, tantalum and indium. In addition to wear resistance, it has good oxidation resistance, corrosion resistance and welding performance. Wear-resistant parts can be made, and they can also be used as coating materials, which can be coated on the surfaces of other matrix materials by surfacing and spraying processes. Nickel-based alloy powders include self-fluxing alloy powders and non-self-fluxing alloy powders.

Non-self-fluxing nickel-based powder refers to nickel-based alloy powder without B or Si or with low B and Si content. This kind of powder is widely used in plasma arc, spray coating, flame spray coating and plasma surface strengthening. Mainly includes: Ni-Cr alloy powder, Ni-Cr-Mo alloy powder, Ni-Cr-Fe alloy powder, Ni-Cu alloy powder, Ni-P and Ni-Cr-P alloy powder, Ni-Cr-Mo-Fe alloy powder, Ni-Cr-Mo-Si high wear-resistant alloy powder and Ni-Cr-Fe-Si alloy powder.Nickel-based self-fluxing alloy powder was formed by adding proper amount of B and Si into nickel alloy powder. The so-called self-fluxing alloy powder, also known as eutectic alloy and hard-faced alloy, is a series of powder materials formed by adding alloying elements (mainly boron and silicon) with low melting point eutectic into nickel, cobalt and iron-based alloys. There are no Ni-B-Si alloy powder, Ni-Cr-B-Si alloy powder, Ni-Cr-B-Si-Mo, Ni-Cr-B-Si-Mo-Cu, high Mo-Ni-based self-fluxing alloy powder, high Cr-Mo-Ni-based self-fluxing alloy powder and Ni-Cr-W-C-based self-fluxing alloy powder in common use.

Nickel-based shape memory alloy

Nickel alloy containing 50 (at)% titanium. The recovery temperature is 70°C, and the shape memory effect is good. The recovery temperature can be changed in the range of 30~ 100°C by changing the proportion of nickel and titanium in a small amount. It is mostly used to manufacture self-expanding structural parts used in spacecraft, self-excited fasteners used in aerospace industry, artificial heart motors used in biomedicine, etc.