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Nanoindentation testing method for elastic moduli of austenite phase and martensite phase of shape memory alloy

A technology of elastic modulus and memory alloy, applied in the direction of testing the hardness of materials, etc., can solve the problems that cannot be used as mechanical parameters.

Inactive Publication Date: 2016-04-20
SOUTHWEST JIAOTONG UNIV
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Problems solved by technology

The traditional nanoindentation method is mainly used to measure the mechanical properties of single-phase materials. For phase change materials such as shape memory alloys, if the Oliver-Pharr method is used directly to obtain the elastic modulus, it will be austenite and martensite. The mixed elastic modulus of the two phases cannot be used as an effective mechanical parameter

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  • Nanoindentation testing method for elastic moduli of austenite phase and martensite phase of shape memory alloy
  • Nanoindentation testing method for elastic moduli of austenite phase and martensite phase of shape memory alloy
  • Nanoindentation testing method for elastic moduli of austenite phase and martensite phase of shape memory alloy

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Embodiment Construction

[0029] The present invention will be further elaborated below by means of the accompanying drawings and examples.

[0030] figure 1 shows the flow of a nanoindentation measurement method for the austenite and martensite elastic moduli of shape memory alloys, the austenite elastic modulus E a and the martensitic modulus of elasticity E m For the definition on the stress σ-strain ε curve, see figure 2 .

[0031] It should be pointed out that the nanoindentation experiments involved in the present invention all use spherical indenters.

[0032] The specific implementation method is described as follows:

[0033] Step 1. Carry out a small depth indentation experiment, requiring h m / R≤0.001, calculate the austenite elastic modulus E by formula 1 a ;

[0034] P m = 4 E a h m ...

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Abstract

The invention provides a nanoindentation testing method for the elastic moduli of an austenite phase and a martensite phase of a shape memory alloy. The method comprises the following steps: multiple nanoindentation experiments at different depths; data processing by using the Oliver-Pharr method on the basis of experimental results; and regression analysis via empirical formulas obtained by using the Hertz contact theory and parameter analysis so as to obtain the elastic moduli of the austenite phase and the martensite phase. The testing method is simple in principles and easy in steps and can rapidly obtain the elastic moduli of the austenite phase and the martensite phase by implementing the nanoindentation experiments at different depths and using the calculation formulas put forward; and formulas used in the process of calculation are based on theories, experimental results are highly reliable, the process of a data processing algorithm is intelligible, and the data processing algorithm can be easily programmed.

Description

technical field [0001] The invention belongs to a new nano-indentation test method, which is used for measuring the elastic modulus of the two phases of austenite and martensite in a shape memory alloy. Background technique [0002] Shape memory alloy is a kind of smart material, and nickel-titanium-based shape memory alloy is the most superior class of superelasticity and shape memory properties. The material has been widely used in micro-electromechanical, medical, aviation and automotive industries. The superelastic properties of shape memory alloys originate from the transformation between the austenite phase of the cubic lattice structure and the martensite phase of the rhombic cubic lattice structure: during the loading process, once the response stress exceeds the austenite phase When the stress of martensite transformation begins, austenite begins to transform into martensite; when unloading, the elastic unloading of martensite occurs first, and once the stress is l...

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Application Information

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IPC IPC(8): G01N3/42
CPCG01N3/42
Inventor 阚前华徐祥康国政卢福聪方涛
Owner SOUTHWEST JIAOTONG UNIV
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