A strengthening method in which lattice strain created by solute atoms dissolved in the matrix obstructs dislocation motion and raises the strength of a metal. There are interstitial and substitutional types.
Japanese name: 固溶強化
Solid-solution strengthening appears in 3 practice questions across 2 topics, including Heat treatment and metallic materials, High-temperature materials and creep.
Field: Metals and alloys
Solute atoms differ from the matrix atoms in size and elastic modulus, so they distort the surrounding lattice. A dislocation also has compressive and tensile strain fields around it, and the energy is lowered when large solute atoms gather on its tensile side and small ones on its compressive side. As a result, extra force is needed for a dislocation to move past solute atoms. The magnitude of strengthening depends on the differences in atomic size and modulus, and models in which it is proportional to c^(1/2) (Fleischer) or c^(2/3) (Labusch) in the concentration c are widely used.
Substitutional solutes expand or contract the surrounding lattice almost spherically, so they interact mainly with the hydrostatic component of edge dislocations, and the strengthening is relatively moderate. By contrast, carbon and nitrogen in BCC iron occupy octahedral interstices and create a tetragonal distortion that stretches the lattice strongly in one direction, so they also interact strongly with screw dislocations and produce large strengthening even in small amounts. The yield point phenomenon of mild steel occurs because carbon and nitrogen atoms gather at dislocations and pin them (Cottrell atmospheres), and it gives rise to Lüders bands.
Solid-solution strengthening comes from solute dispersed as individual atoms, whereas precipitation strengthening comes from particles of clustered solute that obstruct dislocations. Because the state of the solute changes little with heat, solid-solution strengthening tends to remain effective at high temperature and carries little risk of weakening over time, as happens with overaging. On the other hand, solute atoms also scatter electrons and lower electrical and thermal conductivity (Matthiessen's rule). In copper alloys where conductivity matters, designs often precipitate the solute out of the matrix rather than leaving it in solution.
Non-heat-treatable aluminum alloys gain their strength from solid-solution strengthening by Mg and from work hardening. The annealed 5052 alloy, with about 2.5% Mg, has a yield strength of about 90 MPa, more than twice the roughly 35 MPa of annealed pure aluminum (1100). In steels, Mn, Si, P and similar elements contribute solid-solution strengthening and are used in designing the strength of high-strength steel sheet. In Ni-based superalloys, large, slow-diffusing atoms such as W, Mo and Re strengthen the matrix in solution and raise high-temperature creep strength. In every case, adjusting the dissolved amount within the solubility limit is fundamental to the design.
Answer: C. The lattice strain field around solute atoms interacts with dislocations and hinders their motion
Solute atoms differ from the host atoms in size and elastic modulus, so they create lattice strain fields around themselves. These strain fields interact with the strain fields of dislocations and pin them, so a larger stress is needed to move dislocations. This is solid-solution strengthening, and the effect is larger the greater the atomic size difference (size effect) and the modulus difference. Within the solubility limit, increasing the solute concentration generally raises strength and slightly lowers ductility. Brass (Cu-Zn), Al-Mg alloys, and Si and Mn in steel are typical examples of solid-solution strengthening.
No. Elements with larger differences in size and elastic modulus from the matrix atoms are more effective. However, if the size difference is too large, little can be dissolved, so the attainable strengthening is also limited by the solubility limit.
Ductility generally decreases somewhat as strength rises, but the drop is often milder than with precipitation strengthening or work hardening. In some cases, such as brass with up to about 30% zinc, both strength and elongation exceed those of pure copper.
Carbon and nitrogen in iron and steel are the typical examples. One of the main reasons martensite is so hard is that supersaturated carbon distorts the lattice strongly and produces intense solid-solution strengthening.
This is solid-solution strengthening, and the effect is larger the greater the atomic size difference (size effect) and the modulus difference.
Which statement about substitutional solid-solution strengt…The 5000 series (Al-Mg) are non-heat-treatable alloys that get their strength from solid-solution strengthening by Mg and from work hardening by cold working.
Which of the following aluminum alloys cannot be strengthen…Besides solid-solution strengthening of γ, it slows the coarsening of γ' and rafting, in which γ' joins into plates under stress at high temperature, greatly raising creep strength.
What is the main purpose of adding a few percent of heavy e…Dislocation Brass Work hardening Nickel-based superalloy Creep Columnar grains Recovery Recrystallization Stainless steel Titanium alloy